Monday

May 4, 2015

May 4, 2015

Total # Posts: 1,484

**Math**

How do you convert C to F? Multiply by 9, divide by 5, then add 32. Multiply 1.1111111... by 9, you get ---- which is equivalent to (it may look nearly the same as, but it is the same) ---- Divide that by 5, to get ----- Now add 32.
*October 8, 2009*

**Math**

Um, possible typo there? If the cards are drawn _with_ replacement, the first card is back in the deck when the second is drawn, and the probability of the second being a diamond is again 13/52?
*October 7, 2009*

**math**

First, draw your triangle so you can see what you're doing. The short side, 12, will be opposite the small angle, 30. We know that the sin of an angle = opposite over hypotenuse. The angle is 30, and we can look up sin(30)=0.5. So opposite (which we know is 12) over ...
*October 7, 2009*

**math**

Consider the line tangent to y^2=4x. It has m = x^(-1/2). At 1,2, that's m=1, so y=x+1. The circles are tangent to this line, so a perpendicular through (1,2) joins their centres. That'll be y=-x+3. So to get our centres we're looking for two points with a distance...
*October 7, 2009*

**7th grade math**

The counting principle is oddly-named, since it mostly involves multiplying :-) It just means that if you can do the first thing x ways, and then in the next step you can do that y ways, then overall you can do the whole thing in x * y ways. Consider a two-digit PIN. How many ...
*October 7, 2009*

**math**

For a rectangle, you need to have sides A and B wide and long. Then you multiply A and B to get the 50 players. This is the same as asking how can 50 be factored into two factors (which don't have to be prime). Start with the prime factors. 50 = 5 * 10 = 2 * 5 * 5 Um. ...
*October 7, 2009*

**algebra 2**

An inverse just undoes what the original function did, so you can get it by doing the opposite of what the original functtion did, in reverse order. g(x) tells you: multiply by -6, then add 5. Its inverse will tell you: subtract 5, then divide by -6. Example: g(2) = 2*-6 + 5...
*October 7, 2009*

**maths**

I don't see a short-cut. Could this just be division practice? I make it two such numbers of 24 possibilities, one of which is 4186, and the other is predictable from that because 8 mod 7 = 1, and the equation (1000a + 100b + 10c + d = 0 mod 7) works out to (6a + 2b + 3c...
*October 7, 2009*

**math**

Forget the halfway for a minute. From the point she fell asleep, she slept twice as long as the rest of the flight after waking. Does that smell like 2/3 + 1/3 to you? Back to the halfway bit... She slept 2/3 of the second half of the flight. She slept 2/3 of half of the ...
*October 7, 2009*

**Math**

You're wrong about one thing; you _do_ know how to do it. You just did it :-)
*October 7, 2009*

**math **

You multiplied by -1/4, I presume: -4x>1/11 -4x (- 1/4) > 1/11 (- 1/4) x > -1/44. That's what I get, too!
*October 7, 2009*

**algebra**

Let's take the first one. We know that any line can be expressed as y = mx + c First we plug in the m given: y = (2/3)x + c. Now, we know that the point (3/2, 9/5) is on this line, so we can substitute these values into our equation to find c: 9/5 = (2/3)(3/2) + c 9/5 = 1...
*October 7, 2009*

**Math**

You typed both 81,700,00 and 81,700,000. I will assume you meant the second, because of the placement of the commas. So Standard form 81,700,000 = 81.7 * 10^6 = 8.17 * 10^7 In scientific notation, we put only _one_ digit before the decimal place, so you will never see 81.7 x ...
*October 7, 2009*

**algebra**

Oops, typo. In case you're confused, I meant "One way to approach it is, as you say, to add -5x to both sides..."
*October 7, 2009*

**algebra**

When you have an equation with just x and y terms, you're looking at a straight line. One way to approach is it, as you say, to add -5 to both sides, and then divide across by 2, so that the LHS just contains y on its own. Then you have it in the form y = mx + c, and you ...
*October 7, 2009*

**algebra**

I think you mean (12-8)(7-4)^3 Just checking, because an extra bracket around like ((12-8)(7-4))^3 would give a different answer. Brackets first. Then powers or roots. Then multiply or divide. Then add or subtract. First do the arithmetic inside the brackets: (4)(3)^3 Now ...
*October 7, 2009*

**Algebra**

To find the y-intersect, you can just set x=0, and see what's left: y + x = -10 y + 0 = -10 y = -10 So (0, -10) is your intersect. This is a straight line, so all you have to do is find two points, and use a ruler to draw a line through them. Let's find the x-intercept...
*October 7, 2009*

**Math**

Just start at the beginning and think it through choice by choice. There are 11 to choose from. How many can you choose? 11. Now you've seen one. Choose another. How many do you have to choose from? 10, 'cos you've already seen one. So how many ways can we choose 2...
*October 7, 2009*

**vocab**

On the same assumption, I see that "chosen" works as well.
*October 7, 2009*

**AP Stats**

Well, $115 is exactly one SD below the mean, so that's handy. A useful guideline is that, moving left to right, over 2SD covers the first 2%; 2-to-1 SD is another 14%, bringing you up to 16%, and 1-to-0 SD covers another 33%, bringing you to the mean at 50% (not quite, ...
*October 6, 2009*

**math - equivalent expression**

An example of the distributive property: 3 * (1 + 2) = (3 * 1) + (3 * 2) x * (a + b) = (x * a) + (x * b) or x(a+b) = xa + xb Where the operators are like this, you multiply the figure outside the brackets into each of the symbols intide the brackets separately. You can also ...
*October 6, 2009*

**GEOMETRY **

Each lilt contains at least one distinct pair. There must be exactly one lilt containing each possible pair. Which axiom number is that? We know that L1 contains {A, B}. Write out the pairs you can make from A, B, C.
*October 6, 2009*

**GEOMETRY **

That allcaps is a bit hard on the eyes. If you want people to read your message, do tone it down and type normally, please. From 2) spoof contains at least two purrs. Call the first two A and B. From 4) there exists exactly one lilt containing them, therefore 1. is proved. ...
*October 6, 2009*

**math**

My bad, Ellie and Reiny, on the second one. My thinker slipped a cog, and I considered y = 1/|11-9x|-6 rather than 1/|11-9x|-6=0. Reiny is correct, of course!
*October 6, 2009*

**math**

Sorry, Ellie, I'm not quite sure what it is you have to do with them - graph them? specify a range for which they are defined, or true in the first case? make a table of values? Anyway, I'll talk a bit about them. The first one says -2 * x^2 < 30. Now, this one is ...
*October 6, 2009*

**arithmetic**

This sounds awkward, but is actually easy. Consider the number 400P. It must end in zero - actually, it must end in 00, since it has 100 as a factor. Therefore its cube root must end in zero. Check this for yourself: the last digit of a cube can be determined by the last digit...
*October 5, 2009*

**AP Calculus**

You're very welcome, Bri. And do look up _why_ that is true sometime. It's quite neat.
*October 5, 2009*

**AP Calculus**

You don't actually have to know the whole function to get its value at one point, if you have other useful information. You can - and should! - look up the background to "Leibniz's law", but it says that f(x)=g(x)h(x) implies f'(x)=g'(x)h(x) + g(x)h&#...
*October 5, 2009*

**Help with deductive reasoning**

Let's take the first one. You can make a syllogism if you have two statements like: (1) If A, then B _and_ (2) Rover is A (3)_then_ you can say that Rover is B Now: (1) If a dog eats Superdog Dog Food, he will be happy. (2) Rover is happy. What is "A" here? it&#...
*October 5, 2009*

**Prorgramming in Java**

I'm not a teacher in this forum, but that's kind of a big lump of a problem just to throw out there and expect help with. You'll probably get more useful help if you break it down into tasks - starting with the writing of the CatalogItem class, I suspect - and then...
*October 5, 2009*

**maths**

regina, in the second part, you ask about the graph. When I was doing this kind of thing, I always used to calculate the x and y intercepts, and then just draw a straight line between. Nowadays there is "Wolfram Alpha" wolframalpha you-know-what on the net
*October 3, 2009*

**math**

The first one is either a typo or a trick, since no number of cm^2 make a litre. Was ir cm^3? There are 1000 cm^3 in a L. By "simplify", I presume the question means convert to one unit - either pounds or ouncez. There are 16 oz in a lb, so one pssible answer is (10...
*October 3, 2009*

**math**

Assuming the question was "Find the value of the digit 5 in 35,791" you are absolutely right!
*October 3, 2009*

**Statistics**

Since the flight is always fully booked, we can say that the luggage weight's mean is 8000 and the SD is 2000. We're interested in the number of flights that is more than (300 / 2000 =) .15 SD above the mean. Now we go to a z-score table - Google will provide, if you ...
*October 3, 2009*

**maths**

Profit then 30M. Profit later, 210M. Change in profit is obviously 180M, right? OK, so that change is over how many years? 1992 to 1998 - 6 years. Profit changed by 180,000,000 over 6 years, so on average it changed $180,000,000 / 6 per year.
*October 3, 2009*

**algebra**

When you see an inequality, and most other equations, with one variable, your first job is usually to add, subtract, multiply, or divide, to get the variable on its own, isolated from the numbers. Just remember to do the same thing to both sides. This one has three sides, but ...
*October 3, 2009*

**Computers**

Ouch. Typing too fast. Should test in that else that l1 hasn't exceeded 10. But you should get the idea.
*October 1, 2009*

**Computers**

This is one of the classic workhorse situations of programming, a sort-merge, used just about everywhere. You sort two lists, then merge them. The basic idea is this: Establish a pointer to the first (lowest) entry in each list, then Loop while any entries unmerged: 1. Compare...
*October 1, 2009*

**Algebra ll**

Slope-intercept form y=mx +c where m is the slope. You are told that the slope is -4, so the equation muct be like y = -4x + c That rules out one of your choices. Now, of the other two, the equation must be true for the point (1,2). So which of these is true? 2 = -4 * 1 + 6 2...
*September 30, 2009*

**math**

Think about the line y=-1. What does it look like? It's all the points where y is -1: (0, -1), (2, -1), (-2000, -1)... so it's a line straight up and down. Any line perpendicular to is must be straight across, so it must be of the form x = something, where all the ...
*September 30, 2009*

**8th grade math**

Write down the prime factors of each. Look at all the factors, of both numbers, together. The LCM will be the smallest set of this list from which you can make either of the two original numbers. Example: 30 = 2 * 3 * 5 24 = 2 * 2 * 2 * 3 So we have 2, 2, 2, 2, 3, 3, 5 to ...
*September 30, 2009*

**math**

Yes. You want the two big digits in the tens place for the big one, and you want them in the units place for the small one. So 41 + 32, or 42 + 31, and 14 + 23 or 13 + 24 are the best you can do.
*September 30, 2009*

**C Programming**

Oops. I got the bracket messed up in the pseudocode and left a <= instead of a < in the while.
*September 30, 2009*

**C Programming**

I doubt that it was too long, considering the programs you and I posted earlier. Maybe indentation? You could try something like a do loop around your validation, of the form: do } {get heading and display error message if necessary) } while (heading is not valid) e.g. /* ...
*September 30, 2009*

**Math**

I don't know what polygons you drew, but consider this: no matter what path you took, if at any point you are turned to the left of where you started, you must have turned through 90 degrees (plus some integer number of full turns); if at any point you are turned backward ...
*September 29, 2009*

**physics**

A Newton is 1 kg * m / s^2. The force here is 20 kg * 5m / s^2. You should see it clearly from there.
*September 29, 2009*

**Algebra 1**

Yes! That's what I get, too.
*September 29, 2009*

**physics**

Start by calculating the acceleration of the plane as it moves from rest to take-off. It gets up to 80 m/s in 35 seconds, so its acceleration is 80/35 m/s^2. Now you can just plug in the formula for distance travelled under acceleration = ut + 0.5at^2. Initial velocity u is ...
*September 29, 2009*

**C Programming**

Your problem is that you are always doing a CtoF or FtoC conversion, even when it's F to F or C to C. You need to take both choices into account in your conversion logic, not just the one you're converting to. Actually, your approach is a bit convoluted. It can be done...
*September 29, 2009*

**math**

I'm not sure I know what the question is asking. I'm guessing you have to fill in the numbers equal in distance all the wat between 1562 and 1874. There are five numbers missing, so there are six gaps between. What size must a gap be? Well, there are 6 gaps of equal ...
*September 28, 2009*

**Stats**

Sorry about my mental arithmetic error. :-) So 9 months is 2.12 SD. so 1SD is 4.25 months. 1.28 SD is then 5.44 months from the mean, so the mean is 22 - 5.44. Check: working it the other way .84 is 3.57 months, so the mean is 13 + 3.57. Do those agree? Yes, our mean is 16.57...
*September 27, 2009*

**Stats**

90% is 22 months, is 1.28 SD from the mean. 20% is 13 months, is .84 SD in the opposite direction from the mean. Thus, a difference of (22 - 13) months is equivalent to to (1.28 - (-.84)) SD.
*September 27, 2009*

**Stats**

Given the mean and atsndard deviation, you can find the score for an area under the curve, but working backward, given two percentiles and scores, you can work that in reverse. Reading off the numbers from a z-table (I hope you don't have to work it out from the equation...
*September 27, 2009*

**math**

I'm not sure what the question is, but if k + 9 is greater than 12, then what is k greater than? Pretend k is zero. Is k + 9 > 12? Pretend k is 7. Now, is k + 7 > 12? So what must k be greater than? Another way to approach the inequality is to add or subtract the ...
*September 27, 2009*

**Advanced Functions - urgent**

This appears to be from an intro to calculus course. "instantaneous rate of change" is equivalent to slope, so the questions A and B become "what is the slope of the function" at these points. Have you done differentiation? If you have, you should be able ...
*September 27, 2009*

**Algebra 1A**

evaluate (-8b)^2 and -8b^2 when b=10. (-8b^2)= -8b^2=
*September 27, 2009*

**FIN 200**

Collins Office Supplies is considering a more liberal credit policy to increase sales, but expects that 9 percent of the new accounts will be uncollectible. Collection costs are 5 percent of new sales, production and selling costs are 78 percent, and accounts receivable ...
*September 26, 2009*

**pre calculus**

The first pair is very very easy. Remember that a line that passes through the origin must be of the form: y = mx since the intercept is zero. You are told that this line passes through the origin and that the point (-1, 5) satisfies the equation. You should be able to write ...
*September 23, 2009*

**C programming**

Oops, I meant 6 possible answers. While I'm here, remember strcpy puts the value into the string, and strcat appends it to the end of the string. Remember to be sure to declare result to be a char field (more than) big enough for what you're going to put in it.
*September 23, 2009*

**C programming**

It's not too hard. Think that there are only these possibilities: Positive X, Positive Y Positive X, Negative Y Negative X, Positive Y Negative X, Negative Y and zero x and / or y OK, so your program will output one of 5 possible answers. You take in two numbers, call them...
*September 23, 2009*

**math**

Take any digit, say 2. Multiply it by 10. What's the last digit? Multiply that by anything else. What's the last digit?
*September 23, 2009*

**math**

It's a very simple pattern, really. :-) Think what happens to the last digit of any number when multiplied by ten.
*September 23, 2009*

**calculus**

Oops, I didn't calculate the intercepts. My bad.
*September 23, 2009*

**calculus**

I wonder if the second question isn't a little more mean and evil than that? :-) The parabola is upturnd, symmetrical around x=0, like a rounded hill. A tangent to that parabola that forms a side of an equilateral triangle as described would be of the form +/-sqrt(3)x + c...
*September 23, 2009*

**math**

Answered below
*September 22, 2009*

**math**

Answered below
*September 22, 2009*

**college math statistics**

I agree with you on A and B. C: You know that P(over 65) = .12 and the question states that 40% of this group take 5 or more prescriptions. Can you take it from there? D: First figure: 1) How many people under 65 use 5 or more prescriptions and 2) How many people over 65 use 5...
*September 22, 2009*

**math statistics/probability**

Answered above
*September 22, 2009*

**Algebra 1**

Call the number of miles x. Every trip costs at least 1.50, so we can call that a constant that we add to every trip. It is also the only fare if the trip is two miles or less/ In addition to that, every trip over two miles costs an extra 1.20 * x, except for the first two ...
*September 21, 2009*

**algebra**

There is no single "solution" to this equation. You can see that easily: 9 + 3 * 1 = 12 6 + 3 * 2 = 12 so this does not specify a unique x or y, but for any given x, there can be only one y. In fact, it specifies an infinity of (x, y) pairs, that, if you graph them, ...
*September 20, 2009*

**math**

I'd go for "negative y-values are reflected in the x-axis", but my terminology may be out of date.
*September 20, 2009*

**Math**

Apart from the subject, that equation isn't going to peak for x > 0. I think you may have an error in the question.
*September 20, 2009*

**Math**

First, 5:00, 120 minutes, is right. You can do this without algebra. In fact, algebra would only complicate it. In the jargon, 120 is the lowest common multiple (LCM) of 40 and 60. That means that it's the smallest number that both divide into evenly. 40, 80, 120 60, 120 ...
*September 20, 2009*

**Physics - heat**

1 caloris is the amount of energy needed to raise the temp of 1g or water 1 degree. So if it raises 50g by 28 deg, that's how many calories? OK, so we know how many calories affected the water, but we are also told that the burning was only 40% efficient, which means that ...
*September 20, 2009*

**physics**

You're very welcome, Mary. Sometimes, just sometimes, a picture, or graph, or video, is worth much more than a thousand words.
*September 20, 2009*

**physics**

When the rivet goes in, let's say its length is L. As it cools, it shortens a little, so its length is now L-delta(L). But it's holding the two plates, so as it shortens, it pulls them together just a little, by the amount delta(L). What you're thinking is that its...
*September 20, 2009*

**physics**

Consider the amount of contraction in cooling - in _both_ directions. The cross-sectional contraction is a minor negative, but the rivet is much longer than its cross-section, so the contraction along its length is proportionally greater. And, remembering that the rivet is ...
*September 20, 2009*

**Logarithums?**

I don't see why you have to convert it; they are indeed the same thing. I want to draw a graph for this, but I can't :-) In general, you can use the rule that ln(1/x) = -ln(x), so you can simply declare that and be done. I'll try to show an equivalence so it might ...
*September 20, 2009*

**science**

For more details, look up "Newton's law of universal gravitation" on Wikipedia, but the gist is that the force between the Earth and the Moon depends on the product of the masses divided by the square of the distance, and then thetre's a factor g that is ...
*September 20, 2009*

**math**

I think this is not the full question?
*September 20, 2009*

**math**

The brackets mean that you need to add the 8 and the 7 first. 8 + 7 = 15. Now multiply that 15 by 3, and multiply that answer by 2.
*September 20, 2009*

**math (algebra)**

40
*September 20, 2009*

**Algebra I**

Call the numbers A, B and C We know A + B + C = 147 We are told that: B = 2 A + 4 (two times the first number and add 4) and C = 3 A - 5 (five less than three times the first number) This is called substituting. Now we can substitute (2 A + 4) for B whenever we see it. Using ...
*September 19, 2009*

**Science**

What might be the differences between liquids in a mixture? They might have different... what? Boiling points? Freezing points? Density, which in liquids we often measure as specific gravity. If it's a mixture, the two liquids will very probably have different boiling ...
*September 19, 2009*

**physics**

Sorry, missed your followup earlier. I get the numbers you do, but something is funny with the question. h = 3.40t^3 anything with a t^3 term isn't acceleration; it's jerk. Constant jerk, in fact, that would have the chopper well into outer space in 60 seconds! Sorry, ...
*September 19, 2009*

**physics**

How high is the chopper after 2.05 s? call it H H = 3.4 * 2.05^3 m Now from that height, it drops something. I assume we're not taking air resistance into account here, or the question would be much longer. I don't know how accurate the measuure your class uses for g, ...
*September 19, 2009*

**latin**

ad lib. is short for ad libitum meaning at will (more or less) et alia, shortened to et al. (et = and, alia = others) versus (against) gets cut to vs. (why is abbreviation such a long word? :-) Quod (which) vide (see) gets shortened to q.v. cf., short for confer, means compare...
*September 19, 2009*

**physics**

Assume the particle starts at x=0. What is the position after 2.3 s? x = (50 * 2.3) + (10 * 2.3^2) That's how far it has travelled in 2.3s From there the average velocity is easy, I think
*September 19, 2009*

**math**

Scientists and mathematicians tend to avoid pie charts, because humans have a harder time judging angles and areas than line lengths. The Wikipedia page on Pie_charts, which I just visited, shows examples of a pie chart with apparently equal-ish segments that show up as ...
*September 19, 2009*

**physics**

Is the question average speed? Assuming average speed, you must find total distance, then total time, then divide them Time is easy: 24 + 36 + 44 + 13 minutes So how far do you get driving 24.0 min at 63.0 km/h? 36.0 min at 45.0 km/h? 44.0 min at 49.0 km/h? 60 min at 63 kph ...
*September 19, 2009*

**math**

How you present the pie chart is kind of up to you, unless you were given specific instructions. You could put the numbers of deaths, or the percentages, or both. Apparently I can't put a link here, but if you go to the Wikipedia page Pie_chart you will see typical examples.
*September 19, 2009*

**math**

The numbers are close, but not exact since for example alcohol is about 12.6 rather than 13, but yes, you've clearly got it - but be careful; those numbers are degrees, not percent Alcohol is about 3.5%, and that makes about 12.6 degrees of a circle
*September 19, 2009*

**math**

Ayup! 54120 total deaths 510 from murder will be represented by about 3.4 degrees of the circle
*September 19, 2009*

**math**

A useful approach is to take a simpler case Suppose there were just 5 by murders, 30 by accidents, and 65 by tobacco How many would all the deaths add up to? What proportion of all deaths would be by tobacco? So there were 100 deaths, 65 by tobacco So tobacco would be 65% of ...
*September 19, 2009*

**Technology**

What about the zipper? Always my favorite tech story. :-) Or the camera phone? Quite recent, and there's a great story about its invention, which you can find in several places.
*September 19, 2009*

**math**

Multiply both sides by d^2 F(d^2)=G(mM) Divide both sides by F (d^2)=G(mM)/F Now take the square root d = SQRT(G(mM)/F)
*September 19, 2009*

**math**

Well, you have a) one variable per entity, and they are b) discrete rather than continuous, and c) within a reasonable range; the largest is no more than 80 times as big as the smallest, so you won't go wrong with a simple linear graph - column or bar chart. If you had two...
*September 18, 2009*

**college**

If cashews cost $5.00 per pound and peanuts cost $1.50 per pound how do I write the formula to determine how many pound of cashews to mix with 30 pound of peanuts so that the mix will sell for $3.00 per pound.
*September 14, 2009*

**accounting**

The Landis Corporation had 2008 sales of $100 million. The balance sheet items that vary directly with sales and the profit margin are as follows: Cash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5% Accounts receivable...
*September 7, 2009*

**math**

9/14divided by 15/28
*August 18, 2009*