Saturday

February 28, 2015

February 28, 2015

Total # Posts: 10,916

**statistics**

Normally distributed data are symmetric about the mean, so 50% goes above and the other 50% goes below the mean.
*May 26, 2013*

**statistics**

By definition: P(B|A)=P(B∩A)/P(A) So 0.4=P(B∩A)/0.5 Solve for P(B∩A)
*May 26, 2013*

**statistics**

1.0 When data fit exactly onto a straight line, the correlation coefficient is either +1 or -1. If the slope of the line is positive, r=+1. If the slope of the line is negative, r=-1. In this case, the slope=+2, so r=+1.0
*May 26, 2013*

**Math**

Zero. g(x) is the tangent to f(x) at x=-3. Show that this is the case by solving for x in the equation f(x)=g(x) and show that it has a double root.
*May 26, 2013*

**French**

Conjugaison du verbe "avoir" (to have) au présent indicatif: j'ai tu as il a nous avons vous avez ils ont Since your subject is "je", or I, first person singular, we need to use "ai". "as" is for second person singular. Also, ...
*May 26, 2013*

**math**

45-45-90 triangle is isosceles. The other short side is therefore also x. Using Pythagoras theorem, we find hypotenuse²=x²+x²=2x² Solve for hypotenuse.
*May 26, 2013*

**coefficients**

A coefficient is the numerical part of each term. 5x^2+3x+66 has coefficients 5, 3, and 66 for the first, second and third terms respectively.
*May 26, 2013*

**Polymonimals!**

When you have a negative sign preceding parentheses, do an extra step to remove the parentheses: (m^2-m-4)+(m-5) =m^2-m-4+m-5 =m^2-m+m-4-5 =m^2-9
*May 26, 2013*

**vectors problem!!!! help!!!! :)**

You're welcome!
*May 26, 2013*

**vectors problem!!!! help!!!!**

This is the magnitude of the cross product. The cross product is obtained by evaluating the determinant p i j k 2 9 0 13 18 0 which is p=0i+0j+(2*18-9*13)k =-81k The magnitude is therefore 81.
*May 26, 2013*

**Statistics**

I think you have the right formulas, but the wrong N. N equals 5 (count either number of x values or number of y values). So SSx=197-31²/5=4.8 SSy=39000-440²/5=280 Sxy=2760-31*440/5=32 r=Sxy/sqrt(SSx*SSy)=0.87287
*May 26, 2013*

**Statistics**

I was questioning SS(xy) only. We need Sum of xy for calculating other parameters, but not sum of squares of xy. How did you get your answers? I got 197 for SS(x). All of your answers seem to come up a little more than half of mine.
*May 26, 2013*

**Statistics**

I do not know if we use the same terminology. Is SS(x) sum of squares of x? If it is, I get 197. Would it be S(xy) instead of SS(xy), meaning just the sum of the products? Does r mean coefficient of correlation, which has a range of -1 to 1. If you get 7.04, perhaps you are ...
*May 26, 2013*

**help!!!!! Probability!!!::)**

You're welcome! It would be even better if you would not use various aliases.
*May 26, 2013*

**help!!!!! Probability!!!**

Assume die is fair. Rolling twice gives 36 outcomes, of which the second roll is strictly less than the first (successes) can be enumerated as follows: 21,31,32,41,42,43,51,52,53,54,61,62,63,64,65 Count how many successes there are, and divide by the size of the sample space (...
*May 26, 2013*

**math**

There is not much to simplify. Is the integration from a to b or from b to a? Your answer is close, but has the wrong sign and missing a term. Remember that e^0 is 1 and not zero.
*May 26, 2013*

**integral calculus**

You may want to show your work to know how you got your answer. The good news is that your indefinite integral is correct, but off by 1/24, which can be absorbed in the integration constant. Depending on how you integrated, it could give equivalent results of: (3sin(x)^4-2sin(...
*May 26, 2013*

**Engineering science**

Hints: Kinetic energy, KE=(1/2)mv² where m=mass of object (kg) v=velocity (m/s) Potential energy =mgh m=mass in kg g=acceleration due to gravity, m/s-2 h=height above datum in m. To calculate h, you need the distance travelled. For uniform acceleration, distance d, is the...
*May 26, 2013*

**math**

The question gives the length of the original log as 50 cm (unless there is a typo). If the two pieces are equal, then each piece would measure 50/2 cm = 25 cm.
*May 26, 2013*

**Statistics**

Maple can certainly find r, called the coefficient of correlation. The coefficient of correlation, r, for a population can be calculated using the following formula (one of the different forms): r=(nΣxy-(Σx)( Σy)) / √[(nΣx²-(Σx)²)(...
*May 26, 2013*

**Statistics**

Are you expected to use Maple to do this exercise? What are the answers?
*May 26, 2013*

**math**

According to the question, 5.13 is in tens of thousand of dollars, so the correct answer should be $51300, and the $ sign is already given before the answer box, right?
*May 26, 2013*

**math**

"y (in tens of thousands of dollars)"
*May 26, 2013*

**physics**

Acceleration of an object in circular motion is: magnitude = v²/r v = 2 m/s r = 0.5 m Direction is towards the centre of the circle. Mass is irrelevant (unless you need the force on the string).
*May 26, 2013*

**math**

Since the fraction of boys who play the games cannot exceed 1, so 4/7+5/8-1 is the fraction who plays both games. 5/8+4/7 - 1 =(35+32-56)/56 =(67-56)/56=11/56
*May 26, 2013*

**French**

Bravo, c'est une production écrite créée avec soin! A few little things: - "à Dubai mall" : do you mean a shopping centre? (centre commercial) unless it is a proper name, in which case you would write "Dubai Mall". - "...
*May 26, 2013*

**Math**

Let's say we each have two apples. If I give you one apple, you have three and I have one. So the difference is 2 apples. If I give you two apples, you have four and I have none, the difference is 4. We conclude therefore that for every apple I give you, the difference ...
*May 26, 2013*

**Math (Absolute Value Inequality)**

You probably would like to find the value of a. We established that to satisfy the quadratic inequality x^2−11x−210 < 0 -10<x<21 Now substitute this interval into each of the two linear inequalities: x-8<a and 8-x <a (-10)-8<a => a>-18 8-(-...
*May 26, 2013*

**Math (Absolute Value Inequality)**

If we would like to satisfy the condition: x^2−11x−210 < 0, we need to find the roots of x^2−11x−210=0. By factoring, we have (x-21)(x+10)=0 The leading coefficient (of x^2) is positive, so the curve is concave up. => x<0 between -10 and 21. To...
*May 26, 2013*

**Math/Algebra**

The ellipse is centred at the origin (0,0). The standard formula for the ellipse is then x²/a²+y²/b²=1 where 2a=distance between vertices on the major axis =(5-(-5)=10, so a=5 Distance between foci 2c=(4-(-4))=8 so c=4 To find b, we use the relation a²...
*May 26, 2013*

**divide radical**

Hint: factorize the numerator: 2b²+2b-6 =2(b²+b-3) which does not have rational factors. You will need to do a division, which is called the Euclidean division (long division), or another method is the synthetic division. It is a little difficult to show the method ...
*May 26, 2013*

**Maths**

Line with slope a through a point (x1,y1) has the equation: y=a(x-x1)+y1 Putting a=-2, (x1,y1)=-1,6), we get the line as: y=-2(x-(-1))+6 or y=-2x+4 ....(1) Substitute x=4 in equation 1 to find the value of y, which is the required unknown.
*May 26, 2013*

**Geometry**

Without knowing the 8 steps to which you are referring, you can do the following: Factor both numerator and denominator: R(x)=(x-5)(x+6)/[(x-5)(x+4)] You will find the zeroes and asymptotes. Since there is a common factor (x-5), the point f(5) is indeterminate and should be ...
*May 25, 2013*

**MATH315 Elementry Statistics**

Some of the requirements of a binomial model are: 1. probability of success is known and does not vary over the experiment 2. Has exactly two outcomes (head/tail, success/failure). 3. has one or multiple steps 4. is a random experiment
*May 25, 2013*

**Math**

Not sure if I understood the question. Does it mean that we need to write the formula A=(B+b)h/2 without using parentheses AND without using the multiplication sign? Would it be: A=Bh/2 + bh/2
*May 25, 2013*

**Math**

Yes, the calculation is correct for the net price factor.
*May 25, 2013*

**math :)**

You're welcome!
*May 25, 2013*

**math**

Hint: a sector is a pie-piece, similar to a slice of pizza. The area of a sector of a given radius is proportional to the central angle. Area of Sector -------------- Area of circle central angle =------------- 360°
*May 25, 2013*

**math :)**

You're welcome!
*May 25, 2013*

**math**

Do it just like normal subtraction, except that when you borrow 1 degree, it becomes 60 minutes, ... 41-20-26 23-39-56 -------- 17-40-30
*May 25, 2013*

**PHYSICS**

Does it come with a diagram?
*May 25, 2013*

**chemistry**

Zn+2HCl -> ZnCl2 + H2 5.5 g of Zn = 5.5/65.382 M =0.0841 M 25 ml of 0.05M HCl = 25/1000*0.05 M = 0.00125 M < 0.0841/2 So the quantity of HCl governs. Assuming all HCl is consumed, amount of Hydrogen = 0.00125/2 M = 0.000625 M Convert that to the required temperature and ...
*May 25, 2013*

**French :)**

Je vous en prie!
*May 25, 2013*

**French**

Give it a try! You must know the name.
*May 25, 2013*

**French**

camping is an English word borrowed by the French language which means 1. the activity of camping 2. camp-ground. "Comment s'appelle" is an expression which translates to "what do you call ...." "ce" => this "terrain de camping"...
*May 25, 2013*

**math :)**

You're welcome!
*May 25, 2013*

**math**

If the length of one of its sides is x. Then x/2 is half the side. An altitude divides the equilateral triangle into two congruent right triangles, each with half of one side (x/2) as the short side, the altitude as the long side, and the side (x) as the hypotenuse. So by ...
*May 25, 2013*

**math :)**

You're welcome!
*May 25, 2013*

**math**

a' ÷ a = b' ÷ b so a' = b' × a / b
*May 25, 2013*

**math :) **

You're welcome!
*May 25, 2013*

**math**

Do you mean sin-1(0.398) = ? ° ? ' ? " = 23.45320822° multiply the decimal part by 60 =23°27.19249' multiply the decimal part by 60 =23°-27'-11.55" (approx.) =23°-27'-12" (nearest second)
*May 25, 2013*

**math**

Every 5 minutes, the minutes hand turns 30° If it turns 360° (from 12 to 12), then the distance is 43.96. You can use proportions to find how much distance the tip travels from 1 to 4.
*May 25, 2013*

**math**

If the 7-inch hand goes through a complete circle, it would travel the equivalent of the circumference of a circle of radius 7 inches. Use Circumference = 2πr How far would the tip travel from 1 to 4 o'clock?
*May 25, 2013*

**probability**

See response to your previous post: http://www.jiskha.com/display.cgi?id=1369507871
*May 25, 2013*

**French**

According to the Petit Robert dictionary, it also stands for vélo tout-terrain, which means mountain-bike. So the meaning can differ from one country to another.
*May 25, 2013*

**French**

Véhicule tout-terrain
*May 25, 2013*

**Statistics**

Here are some numbers for checking your answer. approximately y=2.3x+23 The correlation coefficient is over 0.99.
*May 25, 2013*

**algebra**

Reflection about the y-axis is given by: (x,y)-> r(-x,y)
*May 25, 2013*

**Math**

It is a binomial distribution, with p=0.6 (probability of success) q=0.4 (probability of failure) n=5 (number of steps) r=2 or 3 (number of successes) P(n,r)=nCr p^r q^(n-r) P(5,2)=5C2 0.6^2 0.4^3 =(5!)/(3!2!) 0.6^2 0.4^3 = 10(0.36)(0.064) = 0.2304 Similarly, for 3 tails, r=3...
*May 25, 2013*

**simple interest and compund interest.**

It sounds like you have difficulties putting numbers into the formula you gave me, so I will do the first one for you. You can attempt the second one as a confirmation. A=P(1+rt) Since A=amount, so Amount=P(1+rt) P=3000, so Amount=3000(1+rt) r=0.03 (3%), so Amount=3000(1+0.03t...
*May 25, 2013*

**simple interest and compund interest.**

A=amount P=principal=$3000 r=0.03 t=number of years, missing from question. Take out your calculator and calculate according to the formula: A=P(1+rt) Here i=5%=0.05/12 (compounded monthly n=6 years = 6*12=72 months P=principal (unknown) A=final amount = $15000. From A=P(1+i)^...
*May 25, 2013*

**HealthCare Finance Bonds**

Sorry, meant "going back to IRS"
*May 25, 2013*

**HealthCare Finance Bonds**

a. At 12% yield, with 40% going back to IRA, he nets 12%(1-0.4)=7.2% b. and c dependent on answer of a, will give you a chance to try them.
*May 25, 2013*

**Statistics**

Here are a few articles that explain what a p-value is, with examples. One of them is a youtube link, if you so prefer. http://www.stat.ualberta.ca/~hooper/teaching/misc/Pvalue.pdf http://www.youtube.com/channel/HCM26EC2x5oEU http://en.wikipedia.org/wiki/P-value
*May 25, 2013*

**expressions**

Since the rate of filling is constant, it is a rule consisting of a linear expression. Let H=height, and x=number of days since today (day 0). Since water rises 2 feet per day, today's height, H = 14 feet. So the rule is then H = 14+2x where 2 = additional depth per day 14...
*May 25, 2013*

**exponents :)**

You're welcome!
*May 25, 2013*

**exponents**

#4 and #5 are both correct. For #8, it is x^8/y^8, since the question requires positive exponents. (You could have written it as x^8y^-8.) 1. 1/125 is 1/5^3. See if you can find the correct answer. 2. d^4*d^6 is d^10, so correction required. 3. the minus sign before the ...
*May 25, 2013*

**scientific notation am i doing it right?**

signature.
*May 25, 2013*

**scientific notation am i doing it right?**

Sorry, finger faster than the brain, forgot to change since last post.
*May 25, 2013*

**scientific notation am i doing it right?**

#1 is correct. The power of 10 refers to the number of positions the decimal point has to be moved, not the number of zeroes. So for #2, it should be 9.82000*100000=982000 Similarly, for #3, 9x10^3=9/1000=0.009 I will leave #4 for you to try.
*May 25, 2013*

**scientific notation am i doing it right?**

All correct, well done!
*May 25, 2013*

**Sequences**

Find the rule for number 2, which is a geometric series. You can tell if it is a geometric series by dividing any term by the previous. If the quotient is the same, then it is a geometric series. The rule for a geometric sequence is: t(n)=ar^n and r is the quotient by dividing...
*May 25, 2013*

**Sequences**

Let the nth term of the arithmetic sequence be t(n)=ax+b then t(1)=a(1)+b=7 t(2)=a(2)+b=12 Subtracting, we find 2a-a=12-7 which gives a=5 Substitute back into the formula, t(1)=5(1)+b=7, so b=2 the complete rule is then t(n)=5x+2 The nineteenth term is therefore t(19)=5*19+2=...
*May 25, 2013*

**polynomials am i doing it right?**

You're on the right track... 1. expand it and write it out when it is a subtraction: (x^4+7x^3+7)-(2x^4-4x^3+1) = x^4+7x^3+7) -2x^4+4x^3-1 = -x^4 + 11 x^3 + 6 2. space out your terms to avoid losing some of them. (3n^3 + n^2 -n -4)+(5n^3 -4n^2 + 11) = 3n^3 + n^2 -n -4 + 5n...
*May 25, 2013*

**How to get quick responses to your math questions**

Also, - DO check that the question you are about to post is complete and accurate before pressing the "post" button. - Do not omit parentheses. If the numerator or denominator of a fraction has more than one term, you need parentheses around them when you transcribe ...
*May 25, 2013*

**How to get quick responses to your math questions**

Math is a wide subject, ranging from K to 11, college and university. Then there is algebra, trigonometry, geometry, arithmetic, calculus, number theory, ... etc. Not all teachers answer all math questions (many do). If you would give a little more detail on which branch of ...
*May 25, 2013*

**Physics**

Hint: Find the resultant of the two given forces. The third force (which keeps the resultant in equilibrium) is a force which is equal in magnitude to the resultant, but opposite in direction.
*May 25, 2013*

**Maths**

Use the property of intersecting chords PA*PB=PC*PD In this case the chords intersect outside of Γ. Also, if T is the tangent to Γ passing through P, then PA*PB=PC*PD=PT²
*May 25, 2013*

**math**

Trade discount = $679.95*0.30
*May 25, 2013*

**trig**

So on the Cartesian plane, it is in the fourth quadrant, with x-y as (900,-500). Atan(-500/900)= -29° approximately. So the bearing is S61°E.
*May 25, 2013*

**Calculus**

Use substitution, p=sin(x), dp=cos(x)dx I=∫ydx =∫cos(x)(2sin(x)-1)^6dx =∫(2p-1)^6 dp Substitute again, u=2p-1, du=2dp I=∫u^6 (dp/2) =u^7/7 ÷2 + C Now back substitute u=2p-1=2sin(x)-1 I=(2sin(x)-1)^7 /14 +C
*May 25, 2013*

**Math/ Algebra**

Rewrite the equation in symmetric form x/a + y/b = 1 where a and b are the x- and y-intercepts respectively. y/2 -3x/5 = 1 can be rewritten as: x/(-5/3) + y/2 = 1 Identify the intercepts and graph accordingly.
*May 24, 2013*

**Math**

15/20/20 is a successive discount of 15%, followed by 20% on the discounted price, and finally another 20% of the doubly discounted price. For example, $1000 with a trade discount of 15/20/30 would have a final discounted price of $1000*(1-0.15)(1-0.20)(1-0.30)=$476 So the ...
*May 24, 2013*

**Math/ Algebra**

See http://www.jiskha.com/display.cgi?id=1369451313
*May 24, 2013*

**Math**

p=probability of scoring (success) = 0.8 q=probability of not scoring (failure = 0.2 Assuming the probability does not change over time and is independent of previous results, then we can apply the binomial distribution: P(7+ out of 8) =8C7*0.8^70.2+8C80.8^8 =0.34+.17 =0.50 (...
*May 24, 2013*

**statistics**

Ah! I see it now. "y (in tens of thousands of dollars)" That might be the culprit.
*May 24, 2013*

**statistics**

Did you put $5.13 or 5.13?
*May 24, 2013*

**Statistics**

There are different ways to find the regression line. Do you know which one you are supposed to use? It should be around y=-0.6x+310. Try to calculate the coefficients and we can check you answer. Do specify the method, and work details if you can.
*May 24, 2013*

**statistics**

If you are working on the computer, you have to get the answer exactly right. It asked for the answer to 2 decimal places. If you put three (3.625), it could mark you wrong. On the other hand, there are two ways to round it to 2 decimal places. Most people round it up when it ...
*May 24, 2013*

**Math - please help**

The height is 280 ft. Distance from apex to mid-point of base = 356.1 ft = slant height. Area of one side = (1/2)base*slant-height then choose the correct answer.
*May 24, 2013*

**Calculus**

Let f(x)=sqrt(1+6x) then f'(x)=3/sqrt(6*x+1) and f'(0)=3 Thus the slope of the curve is 3 at x=0. f(0)=1 means that the tangent to the curve passes through (0,1)=(x0,y0). So the linearization is y=Ax+B =Slope(x-x0)+y0 =3(x-0)+1 =3x+1 Identify A and B for your answer.
*May 24, 2013*

**Maths**

For x near 1, you can use linearlization, which is f(x)=f'(1)(x-1)+f(1) =(1/8)x+f(1) Therefore, within the errors of the linearization, f(x)-f(1) = (x-1)/8 (approximately)
*May 24, 2013*

**geometry - missing information**

To scale or not, we don't get to see it. So we depend on you to describe the figure.
*May 24, 2013*

**please answer simple stat any tutor**

Think of the test as μ1>μ2 Is the solution of μ1 on the left, right or both sides of μ2?
*May 23, 2013*

**algebra**

slope of line y=(2/5)x+7 is (2/5) Slope of line perpendicular to it is -(1/slope)=-5/2.
*May 22, 2013*

**Frenchhhhhhhhhh**

All the cases are direct objects, so you need to replace them by le/la or les (not "des")depending on whether the nouns you are replacing are in singular or plural, and masculine or feminine. There is an extra caution in French is that the pronouns of direct objects ...
*May 22, 2013*

**Frenchhhhhhhhhh**

Replace by what?
*May 22, 2013*

**Algebra - clarifications required**

y=2x=1 is not an equation of a line. Please clarify the typo.
*May 21, 2013*

**Algebra - clarifications required**

1. slope = 15/12 2. slope = -5/4 3. slope = ? (two equal signs, so the sign of the slop could go either way. Please clarify.
*May 21, 2013*

**pre calc**

If sin(x)=-3/5 in Q3, then cos(x)=-4/5 (using cos²(x)=1-sin²(x)) Similarly, cos(y)=5/13 in Q1 means sin(y)=12/13 sin(x-y)=sin(x)cos(y)-cos(x)sin(y) =-3/5*5/13 - (-4/5)*12/13 =(-15+48)/65 =33/65
*May 21, 2013*

Pages: <<Prev | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | **16** | 17 | 18 | 19 | 20 | 21 | 22 | Next>>