Thursday

September 18, 2014

September 18, 2014

Total # Posts: 25,054

**math challenge**

2 hours is 7200 seconds. one day is 1440 minutes. so, ...
*August 8, 2014*

**Algebra**

6.0 <= pH <= 6.5
*August 8, 2014*

**Algebra**

10 <= c <= 12 The middle time is (10+12)/2 = 11 Each extreme is only 1 away from 11, so |c-11| <= 1
*August 8, 2014*

**maths**

8 hours means $32 The rest must be in tips, or at least $118
*August 8, 2014*

**Algebra**

the total points are now 68+78+90+91 = 327 To average 85 on 5 tests, you need 5*85 = 425 So, how many points short is that?
*August 8, 2014*

**math**

since c = 2πr, r = c/2π since a circle has a = πr^2, a = π(c/2π)^2 = c^2/4π the square has perimeter 4*4π = 16π so, the circle has area a = (16π)^2/4π = 64π
*August 8, 2014*

**Maths**

10 = 2p-4 p = 7
*August 8, 2014*

**Math 221**

take a read here: https://people.richland.edu/james/misc/acmeth.html
*August 8, 2014*

**Algebra 2**

Read up on hexagonal numbers. You can get started here: http://en.wikipedia.org/wiki/Hexagonal_number
*August 7, 2014*

**Algebra 2**

is there a common difference? is there a common ratio? How about showing some effort here?
*August 7, 2014*

**Algebra 2**

If the 3rd entry were 116, it'd be arithmetic, with d=113.5 But as it is, it's neither
*August 7, 2014*

**Algebra 2**

what's the problem? Just write them out: a_1 = 0 a_2 = 5a_1 + 7 = 5*0+7 = 7 a_3 = 5a_2 + 7 = 5*7+7 = 42 and so on
*August 7, 2014*

**Algebra 2**

a_1 = -5 a_2 = 2(-5)+7 = 3 and so on
*August 7, 2014*

**Algebra 2**

a_1 = 9 a_2 = 3*9 = 27 and so on
*August 7, 2014*

**Math 221**

first note that each term has a w in it, so w(9-w^2) Now recall that a^2-b^2 = (a-b)(a+b), so since 9-w^2 is the difference of two squares (3^2-w^2), we have w(3-w)(3+w)
*August 7, 2014*

**Algebra 2**

Since you have figured r, and a = 0.48, Tn = 0.48*2.13^(n-1) T12 = 0.48*2.13^11 = 1965.25 S12 = 0.48(1-2.13^12)/(1-2.13) = 3703.98
*August 7, 2014*

**Algebra 2**

Clearly, a_n = 5*4^(n-1) So, S_16 = 5(1-4^16)/(1-4) =
*August 7, 2014*

**Algebra 2**

Sure. It's all clearly explained. For the first one, a_1 = 112 a_2 = -9.5*112(1-112) = 118104 and so on. Similarly for the other example.
*August 7, 2014*

**trig**

review your trig function definitions. I think that 41/x = tan 65 However, as your language is almost incomprehensible, it's hard to be sure.
*August 7, 2014*

**Physics**

In the absence of other factors, both will hit the ground at the same time, because the force of gravity is all that's acting on them, making them fall at the same speed. The horizontal speed of the bullet has no effect on the pull of gravity. However, in real life, the ...
*August 7, 2014*

**math**

b/g = 9/8 b = g/2 + 15 So, to start with there were 27 boys and 24 girls
*August 7, 2014*

**computers**

I'd say it's an IP address, as discussed here: http://technet.microsoft.com/en-us/library/cc958048.aspx and also, no doubt, in your study materials...
*August 7, 2014*

**math**

we have two points: (3,26) and (7,18) You are correct that y = -2x+b So, plug in either point. For example, 26 = -2(3)+b 26 = -6+b b = 32 y = -2x+32
*August 7, 2014*

**math**

no idea what "b" represents. And with only one data point, we cannot determine anything else. What was the starting pressure? Or, how much pressure did it lose each day? Please make sure your posting accurately reflects the problem as presented, maybe with some ...
*August 7, 2014*

**math**

a cubic foot is 12^3 = 1728 cubic inches. So, the quart weighs 60/1728 * 60 = 2.08 pounds But then we knew that, since "a pint's a pound, the world around."
*August 7, 2014*

**physics**

Just convert the data to rectangular coordinates: 11 @ 88° = 0.0349,10.9933 6.8 @ 115V = -2.8738,6.1629 so, now you want (x,y) such that 0.0349+x = -2.8738 10.9933+y = 6.1629 Then convert that (x,y) back to polar avlues.
*August 7, 2014*

**Math**

2^3 = 8 5^-2 = 1/5^2 = 1/25 so, (a) = 8/25 You cannot simply disregard the negative sign of the exponent, nor willy-nilly move items from bottom to top. You have directly replaced 2^-2 with 2^3 and 1/a^4 with a^4. 2^-3 = 1/2^3 = 1/8 So, (b) = 1/(8a^4)
*August 7, 2014*

**MATH(HELP)**

I believe your previous post said that there were then 30 more guppies than in the beginning. That means that there were 120 to begin with, since adding 1/4 of 120 means adding 30. However, that leaves us nothing to do with the goldfish or angelfish. I suspect you have still ...
*August 7, 2014*

**MATH - eh?**

list the facts: g/a = 2/3 a = 2/3 f The shop keeper decided to replace 1/4 of the guppies with some angelfish. The number of angelfish she added was equal to the number of the guppies she replaced. well, duh. Both sentences say the same thing. The last sentence leaves us ...
*August 7, 2014*

**math**

well, you have the equation. How many weeks from the time she started saving, until Christmas? $25/week, babe. I assume you know how many days per week . . .
*August 7, 2014*

**math**

looking at the data, it appears she saved #25 each week. So, after x weeks, her saving y would be y = 25x You can work into that by noting that if y = mx+b when x=7, 175 = 7m+b when x=15, 375 = 15m+b so, 8m = 200 m = 25 Now you have y = 25x+b plugging either point shows that b...
*August 7, 2014*

**math**

Sounds like a good plan. Was there a question in there somewhere?
*August 7, 2014*

**Geometry**

consider how many reds and the total cards there are for each draw. You multiply the chances for each event, giving 26/52 * 25/51 * 24/50
*August 7, 2014*

**Math**

Looks like 12 to me, since 144 = 12*12
*August 7, 2014*

**spelling mistakes**

theree guest lectures come from CMC hospital to give the trainee and her fellowmates a common introduction above community developement.
*August 7, 2014*

**Statistics**

well, 3000 is 1 std above the mean. So, check your Z table for the area of the tail above Z=1. Or, play around at http://davidmlane.com/hyperstat/z_table.html
*August 7, 2014*

**physics**

The average velocity is zero, but the speed is not. The total distance covered is 2d. The total time taken is d/40 + d/60 = 5d/120 So, the average speed is 2d/(5d/120) = 48 km/hr
*August 7, 2014*

**Math**

5[5m-(m+8)]> -4(m-1) 25m - 5(m+8) > -4m + 4 25m - 5m - 40 > -4m + 4 24m > 44 m > 11/6
*August 7, 2014*

**mathematics**

2(l+b) = p l+b = p/2 l = p/2 - b
*August 7, 2014*

**math - eh?**

Regardless of x, 2+3 = 5 Better try proofreading
*August 7, 2014*

**math**

44-(4x+5)< 2(x+2)+x 44-4x-5 < 2x+4+x 39-4x < 3x+4 35 < 7x 5 < x
*August 6, 2014*

**Calculus-Math**

since x^n/x = x^(n-1), y = 2x^(7/2)/x = 2x^(5/2) y' = 2(5/2)x^(3/2) = 5x√x
*August 6, 2014*

**statistics**

If there are n questions, there are 2^n ways to select a set to answer. That assumes that refusing to answer any at all is also an option. Read up on power sets.
*August 6, 2014*

**math test review**

since w = 25r, we need to increase by 3r, making the result 28r, which is always divisible by 7, since 7 divides 28, regardless of r.
*August 6, 2014*

**math corrections**

In that case, the speed ratio is 250/300, so the teeth ratio will be 300/250 * 30 = 36
*August 6, 2014*

**math corrections**

#2 A pair of pants sells for $6 more than 75% of its price of the pants? The question makes no sense. #4 (A) 0.750 - 0.625 = 0.125 But that is the difference in the diameter. The wall thickness is the difference in radius: half that, or 0.0625 #14 (D) since AB = 40°, <...
*August 6, 2014*

**math**

what, no calculator handy?
*August 6, 2014*

**math**

we need 1.50x + 10[x/30] >= 450 x >= 246.3 check: 1.50*246 + 10*8 = 449 His next sale will push him over $450
*August 6, 2014*

**Geometry**

the pentagon consists of 5 triangles, each with altitude 6.5 and base 9.4 Now it's easy, right?
*August 6, 2014*

**Geometry - !!**

Love it!
*August 6, 2014*

**Geometry**

Hello ... I mean sin -π/6 That is, because 2 cos θ/2 sin θ/2 = sinθ
*August 6, 2014*

**Geometry**

Hello... 2cosθsinθ = sin2θ so, what's sin -π/3?
*August 6, 2014*

**Math**

reduced. Actually, there is a link to the parts of a subtraction problem. In words, we have minuend - subtrahend ---------------- difference That is, the minuend is diminished by the amount subtracted (the subtrahend), yielding the difference. *sigh* it seems folks have lost ...
*August 6, 2014*

**statistical analysis**

sort the values in order The median is the middle value - there are the same number of values above and below it. since there are an even number of values, there is no center value, so average the two center values.
*August 6, 2014*

**college algebra**

looks good to me.
*August 5, 2014*

**Geometry**

Draw a diagram. If half the chord has length x, you have a right triangle. 5^2+x^2 = (5√3)^2 x^2+25=75 x^2=50 x = 5√2 So, XY = 10√2
*August 5, 2014*

**Geometry**

one of the "standard" right triangles is 8-15-17.
*August 5, 2014*

**math**

g(x) = x^3 - 9x^2 + 2x + 48 Look for the easy roots first: 1,2,3. A little synthetic division quickly shows that g(x) = (x+2)(x-3)(x-8)
*August 5, 2014*

**Math**

Hint. If the dining room has side x, then one side of the kitchen must also be s, and the width is 14. So, just add up the areas: x^2 + 14x = 275
*August 5, 2014*

**Math**

you know that ax^2+bx+c has its vertex at x = -b/2a. Here, that means the vertex (maximum no. tickets) occurs at x = 11 days
*August 5, 2014*

**math**

since 18-3+6 = 21, I'd say the blank holds a 4, since 12/4 = 3 Do the others in like wise.
*August 5, 2014*

**math**

17-3x5+4/2 17-15+2 4
*August 5, 2014*

**Algebra 2**

I suspect a notational problem. Why the -4(6)n? Is there supposed to be an exponent, as in 2^3=8? Do you mean -4*6^(n-1) ? That is, the terms are -4,24,-144,... Anyway, just plug your numbers into the formula for the sum of a geometric sequence. Sn = a (1-r^n)/(1-r)
*August 5, 2014*

**Mathematics literacy**

I suggest you provide some details. Normally, simplifying ratios is nothing more complicated than reducing fractions.
*August 5, 2014*

**math**

You appear to be given two points, not the slope and one point.
*August 5, 2014*

**advance algebra**

your algebra may be advanced, but your posting skills could use some improvement. I see what appears to be two points. So, what's the point? Or, they may be two intervals, or two vectors.
*August 5, 2014*

**Calculus-Math**

well, clearly, since f = 9g+h f' = 9g'+h', so f'(8) = 9g'(8)+h'(8) = 9*5-3 = 42 Of course -- that's the answer to the Ultimate Question of Life, the Universe, and Everything! I suspect a typo, since g(8) and h(8) are not used, but maybe there are ...
*August 5, 2014*

**math**

Aside from the trivial 1 and 2, I can only find less than 1,000,000 is 40585 Though it seems likely that there could be others near multiples of 9!
*August 5, 2014*

**Statistics**

for women, 2 ft is 1.6 std below the mean for men, 2 ft is 3.33 std below the mean. So, look those up in your Z table to see the break points. Or, play around at http://davidmlane.com/hyperstat/z_table.html
*August 5, 2014*

**math**

income = rate * customers I see nothing about how many hours she works per customer, so I'll just assume she works one hour each. Actually, we will see that if she works the same constant number of hours for each customer, the number does not matter. If the billable hours ...
*August 4, 2014*

**Gen 499**

what a-(hic)-bout it?
*August 4, 2014*

**Math**

Start substituting: 1/3c = 6b^2, so c = 18b^2 Now, 3b=2a, so 18b^2 = 2(3b)^2 = 2(2a)^2 = 8a^2 I think you left out a +6 somewhere, since there are no such terms shown. Also, if a=3 and b=2, c=72, not 78, so it's a good sign something has been left out. So, if D is the ...
*August 4, 2014*

**algebra - oops**

or, use 15/60 = 1/4 if you want a clser approximation! ...
*August 4, 2014*

**math**

or, you can consider it like this. The boats are approaching each other at 9 mph. The lake is 3 miles wide, so it takes them 1/3 hour to cover all the distance.
*August 4, 2014*

**Calculus III**

Sounds good so far. You can check your answer at http://en.wikipedia.org/wiki/List_of_moments_of_inertia More detailed drawings are found at http://hyperphysics.phy-astr.gsu.edu/hbase/isph.html and the rationale of adjusting the moment after removing the inside sphere is ...
*August 4, 2014*

**Geometry**

The lateral area is just πrs. Don't include the area of the base. so, πrs = 5πs = 65π, so s = 13 So, the height is 12, making the volume v = πr^2 h = π*25*12 = 300π
*August 4, 2014*

**math**

I'd say just 10. That's all there are.
*August 4, 2014*

**calc**

Hmmm. Your answer looks good to me. Although, I'd simplify it to just 3/√3 = √3
*August 4, 2014*

**Chemistry**

Na/NaCl = 23/(23+35.5) = .393 or 39.3%
*August 4, 2014*

**math**

first, clear up the meaning of x=2=2sqrty If you mean x = 2+2√y, then since the curve intersects y=9 at (8,9) we have as usual, two ways to solve it. Using shells of thickness dx, v = ∫[0,8] 2πrh dx where r = x and h = 9-y = 9-(x/2 - 1)^2 v = 2π∫[0,...
*August 4, 2014*

**math**

1000(1+.06/2)^2t <= 800(1+.08/12)^12t t >= 10.8 years
*August 4, 2014*

**Math**

since sin(x) = cos(90-x) sin^2 0° + sin^2 90° = 1 sin^2 5° + sin^2 85° = 1 ... sin^2 45° + sin^2 45° = 1 Now, you have excluded sin^2 0, but since that's zero anyway. You have 9 pairs, plus a single 45, so the sum is 9.5
*August 4, 2014*

**algebra**

since the shadow:height ratio is the same, 25.2/8.4 = x/20.7
*August 4, 2014*

**General knowledge**

What is google, and what does google do?
*August 4, 2014*

**Algebra**

we know that sum 9/3^n is just a geometric series, which converges. 9/(n*3^n) has terms which are even smaller, so it also converges
*August 3, 2014*

**physics**

so, if we name the takeoff point as (0,0) we want the vertex of the parabola to be at (5,4.5) The parabola can thus be written as y = -0.18(x-5)^2 + 4.5 so, at x=0, y' = 1.8 That means the initial angle is θ=60.9° Now you should be able to work out the velocity ...
*August 3, 2014*

**math**

the slope is 1/9, so the point-slope form tells us that y-2 = 1/9 (x+3) now just put that into standard form
*August 3, 2014*

**math**

the line is horizontal, so the y-value does not change. What function stays at -8 for any value of x?
*August 3, 2014*

**math**

using discs, of thickness dx v = ∫[-1,1] πr^2 dx where r = y = 1-x^2 So, v = π∫[-1,1] (1-x^2)^2 dx = 16/15 π Using shells, of thickness dy, we have to account for the two branches of the parabola, so it's easier just to use symmetry and get v = 2...
*August 3, 2014*

**Geometry**

you could draw a semicircle, then draw a tangent line for the stem of the J. Note that the tangent to the circle is perpendicular to the radius.
*August 3, 2014*

**geometry**

(18+2w)(15+2w)-18*15 = 234 w=3 since the frame is 3" wide, you can now determine its dimensions.
*August 3, 2014*

**math**

not much to sketch. Linear functions are just straight lines. So, draw the line through those two points. Done. The only problem is, y is not a function of x. Why not?
*August 3, 2014*

**Grammar**

"I" is singular. So, you need a singular noun.
*August 3, 2014*

**College math**

5logT+2logW+logZ
*August 2, 2014*

**Algebra**

what don't you get? Divide by x+k is the same as divide by x-(-k), so the remainder is p(-k). Same for p(3k). They said the remainders are equal. So, equate the two expressions and solve for k. To check, just evaluate p(x). p(-3/2) = p(9/2) = 47/4
*August 2, 2014*

**geometry**

how about a line, and then a semicircle? Just draw a short perpendicular to the line (don't actually draw it), and then, using that as the radius, draw a semicircle touching the end of the line.
*August 2, 2014*

**geometry**

You drew a line through two points? That's certainly the first step, but it's not the letter E. You still need to draw three perpendicular lines; two at the ends of your line, and one in the middle.
*August 2, 2014*

**math**

(60 / 12^3)*60 = 2.08 But then, we already knew that, since "a pint's a pound, the world around."
*August 2, 2014*

**Math**

You need to review the methods of expressing complex numbers as a+bi and r cisθ. Surely your text has a discussion of the topic. Also, a simple google on "complex numbers polar" will turn up may explanations and examples. √3-i can be plotted as the point...
*August 2, 2014*

**Math**

Tell you what -- why don't you simplify them and we'll check your answers. To get started on (a) √3-i = 2cis -π/6 so, (√3-i)^4 = 16cis -2π/3 now just convert that back to rectangular values.
*August 2, 2014*

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