Wednesday

May 4, 2016
Total # Posts: 34,471

**Math**

If 1/4 inches ---> 1 ft then 1 inch -----> 4 ft and 3 inches ---> 12 ft
*April 13, 2016*

**Math**

Make a sketch, extend the line from the top of the tower to the man until it hits the base line You now have a small isosceles right-angled triange within a larger one. so the smaller one has legs 1.4 m and 1.4 m. So the base of the larger is 1.4+10 or 11.4 m, which means that...
*April 13, 2016*

**Damon,steve,reiny,bobpursley....Any 1 just help me plz**

That's just plain silly.
*April 13, 2016*

**Geometry**

You want the lateral surface area of a cone = π r s, where r is the radius, and s is the "slant" height = π(25)(32) = cm^2
*April 13, 2016*

**Algebra**

This is a GP where a = 26000 and r = 1.03 sum(5) = 26000(1.03^5 - 1)/(1/03-1 = $138,037.53
*April 13, 2016*

**Algebra 2**

if you want your index to be n = 0 , then 9 Σ 2(n+1) n=0
*April 13, 2016*

**Algebra 2**

10 Σ 2n n = 1
*April 13, 2016*

**Probability**

I did the first two for the last two , you are dealing with conditional probability Prob( B given A) = prob(B|A) = prob(A and A)/prob(A)
*April 13, 2016*

**oops - Math**

ignore my previous answers, I totally forgot about the actual probabilities. so for prob(makes first misses seconds and third shots) = (7/10)(3/10)(3/10) = 63/1000 or .063 prob(missing all 3) = (3/10)^3 = 27/1000 so prob(of making at least one shot) = 1 - 27/1000 = 973/1000...
*April 13, 2016*

**Math**

h -- hit m -- miss she has the following cases: hhh hhm hmh mhh hmm * mhm mmh mmm "makes first misses seconds and third shots " --- I see one case, marked with * so prob(hmm) = 1/8 "Makes at least 1 shot" all except mmm so prob(of that event) = 1 - 1/8 = 7/8
*April 13, 2016*

**Math**

No common ratio, thus no geometric sequence however the 2nd, 3rd and 4th form the pattern: -(consecutive even)^2 but then the first term does not follow this pattern. I don't see anything else
*April 13, 2016*

**Trig**

You should memorize the trig ratios is terms of x, y and r so for the point (-1,3) x = -1, y = 3 and by Pythagoras, r = √10 cosθ = x/r = -1/√10 and since secθ = 1/cosθ secθ = -√10
*April 13, 2016*

**math**

There are 3 such multiples, 6,12, and 18 prob(of your event) = 3/18 = 1/6
*April 13, 2016*

**Math**

Are we answering only c) ? c) since there are only reds and whites, and you want prob(red OR white) the prob(red OR white) = 1 that is, 2/10 + 8/10 = 10/10 = 1
*April 13, 2016*

**Calculus Answer Confirming Not Sure Im Right Help?**

For the given substitution , the two statements: lim (∛x-4)/(x-64) , as x --->64 and lim (u - 4)/(u^3 - 64) , as u ---> 4 are equivalent, so lim (∛x-4)/(x-64) , as x --->64 = 1/48 and lim (u - 4)/(u^3 - 64) , as u ---> 4 = 48 They are equivalent ...
*April 12, 2016*

**Calculus Answer Confirming Not Sure Im Right Help?**

let ∛x = u then x = u^3 and as x---> 64, u ---> 4 lim (∛x-4)/(x-64) , as x --->64 = lim (u - 4)/(u^3 - 64) , as u ---> 4 = lim (u-4)((u-4)(u^2 + 4u + 16) , u -->4 = lim 1/(u^2 + 4u + 16), as u --> 4 = 1/(16 + 16 + 16) = 1/48 When you make your ...
*April 12, 2016*

**IMPORTIANT MATH**

let the width be x let the length be y, along the wall so 2x + y = 75 y = 75-2x area = xy = 600 x(75 - 2x) = 600 -2x^2 + 75x = 600 x^2 - 37.5x = -300 x^2 - 37.5x + 351.5625 = -300 + 351.5625 (x - 18.75)^2 = 51.5625 x - 18.75 = appr 7.18 x = appr 25.93 y = 23.139
*April 12, 2016*

**Math**

I ask myself, "how far from the x-axis is my given angle" After I decide which quadrants the given angle is in, I go in II: 180 - angle in III: angle - 180 in IV: 360 - angle e.g. for 330° , which is in IV reference angle = 360-330 = 30° ... for 203, which is...
*April 12, 2016*

**Math**

area of yard = (14x)(19x) = 266x^2 area of circle = π(36x^2) area of remaining yard = 266x^2 - 36πx^2 = (266-36π)x^2
*April 12, 2016*

**Math**

let the monthly rate be i 614( 1 - (1+i)^-48)/i = 24905 (1 - (1+i)^-48)/i = 40.56189 that's toughie to solve, I will use Wolfram https://www.wolframalpha.com/input/?i=solve+614(+1+-+(1%2Bx)%5E-48)%2Fx+%3D+24905 i = .00709 so the annual rate compounded monthly = 12(.00709...
*April 12, 2016*

**finance math**

not that simple let the monthly rate be i 614 (1 - (1+i)^-48)/i = 24905 very tough to solve I will let Wolfram do it https://www.wolframalpha.com/input/?i=sove+614+(1+-+(1%2Bx)%5E-48)%2Fx+%3D+24905 i= .00709283 12i = .08511... or 8.511% per annum compounded monthly
*April 12, 2016*

**algebra**

amt = 800(1.02^22 - 1)/.02 = ....
*April 12, 2016*

**Math question help!!**

Two interpretations are possible for this question. 1. There are 24 students in the class like you said. So if 1/3 are missing, then there are 8 missing, just like Ms Sue had in her previous post. 2. With 1/3 missing, there are 24 students in the class, so the 24 students ...
*April 12, 2016*

**math**

Only A and B make sense although at the end of A , you probably meant to say 4 people at round table
*April 12, 2016*

**Algebra**

width --- x length --- 4x area = x(4x) = 36 4x^2 = 36 x^2 = 9 x = 3 the room is 3 m by 12 m
*April 12, 2016*

**Algebra**

smaller tile --- x by x larger tile ---- x+4 by x+4 x^2 + (x+4)^2 = 40 expand and solve as a quadratic equation. it will factor and solves easily.
*April 12, 2016*

**Algebra**

thoko ---x zandile -- x+4 4 years ago: thoko -- x-4 zandile -- x x(x-4) = 165 x^2 - 4x - 165 = 0 (x-15)(x+11) x = 15 or x = -11 state the conclusion
*April 12, 2016*

**Algebra**

".A student is 6 times younger than her teacher" --> usually stated as, teacher is 6 times older than the student age of student --- x age of teacher ---- 6x 3 years ago: student : x-3 teacher : 6x-3 (x-3)(6x-3) = 36 6x^2 - 21x + 9 - 36 = 0 6x^2 - 21x - 27 = 0 2x^...
*April 12, 2016*

**finance**

amount = 4000( 1.105^5 - 1)/.105 = ...
*April 12, 2016*

**Algebra, math**

Nothing as serious as when WKRP's Les Nessman reported live turkey's dropping from the sky. "As God is my witness, I thought turkeys could fly!!!" -- Arthur Carlson, WKRP in Cincinnati
*April 12, 2016*

**math**

let the unit digit be x let the middle digit be k let the hundred digit be y the original number = 100y + 10k + x the number reversed = 100x + 10k + y so 100x + 10k + y = 100y + 10k + x 99x = 99y x = y We sort of knew that so it doesn't matter what we put in the middle to ...
*April 12, 2016*

**Trigonometry**

a) if the cone is 8 inches high and it is filled with a depth of 8 inches, then the cone is full of water, and the radius of the water level must be 4 inches. Is there a typo here? b) let the height of the water be h, and the radius of the water level be r by similar triangles...
*April 12, 2016*

**math**

You are correct with A = w(w+3)
*April 12, 2016*

**Math**

first year -- 4 = 2(2^1) 2nd year ---- 8 = 2(2^2) 3rd year ---- 16= 2(2^3) can you see the pattern ... 10th year ----- 2(2^10) = 2048 you were right! Did you do it in a different way?
*April 12, 2016*

**Math Help!**

remember, when you divide powers with the same base, keep the base and subtract the exponents, so 7^9/7^3 = 7^9 ÷ 7^3 = ...
*April 12, 2016*

**College Algebra**

No idea what the Malthusian model is, but I will do it my way P = 30,000 e^(kt) , where k is constant and t is years given:when t = 9, P = 60,000 30000 e^(9k) = 60000 e^(9k) = 2 9k = ln2 k = ln2/9 P = 30,000 e^((ln2/9)t) when is P = 1,000,000 ? 30,000 e^((ln2/9)t) = 1,000,000 ...
*April 12, 2016*

**Calculus I**

V = (4/3)π r^3 dV/dt = 4π r^2 dr/dt given: dV/dt = 8π , r = 1 8π = 4π(1) dr/dt dr/dt = 8π/4π = 2 A = 4πr^2 ----> (did you notice that surface area equals the derivative of volume ??) dA/dt = 8πr dr/dt when r = 1 dA/dt = 8π(1...
*April 12, 2016*

**Math Help!**

You are very welcome
*April 12, 2016*

**Math Help!**

correct for both
*April 12, 2016*

**Math Help!**

I noticed in your first question you have 4^a. None of the choices would match that. It had to be 2a(a^2 + 4a) to get a correct answer from your choices. You are using the distributive property which is illustrated by a(b + c) = ab + ac you multiply the stuff sitting in front ...
*April 12, 2016*

**Algebra**

Let the completed job be represented by 1 The first crew worked for 2 days, so they did 2/7 of the job. This leaves 5/7 of the job to be finished by the combined work of the two crews rate of first crew = 1/7 rate of 2nd crew = 1/5 combined rate = 1/7 + 1/5 = 12/35 let the ...
*April 12, 2016*

**Math**

XXXXXX 000901 This follows your wording, but a number such as 000901 would be 901, making it a 3 digit number. Does you number have decimals? then how about 901.000 ? Otherwise your question makes no sense
*April 12, 2016*

**Algebra**

Did you translate the English into Math? I said: x^2 = 4x + 60 now you have a nice and simple quadratic which factors. x^2 - 4x - 60 = 0 solve for x, and take only the positive result
*April 12, 2016*

**Math**

You obviously have a ||gram WXYZ where angle X = 113 In any parallogram, the opposite angles are equal and adjacent angles add up to 180 I don't know what <XYZ= <YZW= <ZWX= is supposed to mean. If 3 angles are to be equal then you must have a rectangle, which ...
*April 12, 2016*

**algebra**

see here http://www.jiskha.com/display.cgi?id=1460427888 Give yourself a nickname, so we can keep track of the questions and avoid duplication.
*April 11, 2016*

**EASY Pre-Algebra**

the four offices are defined and distinct. e.g, you could not simply interchange the office of the secretary with the office of the chairman So you have a permutation, since the order matters. Words such as "committee, select, choose" usually imply a combination
*April 11, 2016*

**Calculus Help Stuck Part 2?**

careful: what happened to your x's in (x-4)/(4-x) ? What really happened is this (x-4)/(4-x) = -1(4-x)/(4-x) = -1[ (4-x)/(4-x) ] = -1[ 1 ] = -1 Any number divided by its opposite = -1
*April 11, 2016*

**Calculus Help Stuck Part 2?**

Step1 for me in any limit question is actually sub in the approach value If you get a real number, that's your answer, all done! so for x = 4, we get 0/0, ok, we got work to do step: if you get 0/0 for simple rational expressions like the above, IT WILL FACTOR. Sometimes ...
*April 11, 2016*

**maths**

cosa = 12/13 construct a right-angled triangle and use Pythagoras to find the sides 5, 12, and 13 since the cosine is + in I or IV, we have two cases: case1: in quad I sina = 5/13, cosa = 12/13 seca + sina = 13/12 + 5/13 = 229/156 case2: in quad IV sina = -5/13, cosa = 12/13 ...
*April 11, 2016*

**interest rates computation**

first investment --- x 2nd investment ----- 4x .07x + .13(4x) = 7965 solve for x
*April 11, 2016*

**algebra**

Follow the same steps I showed you in the previous post Same kind of problem.
*April 11, 2016*

**algebra**

looks like everything is referenced in terms of quarters, so start with : let the number of quarters be x dimes ---- x+138 nickels ---- 2x pennies ---- 14x + 28 Now that you have the NUMBER of coins defined, we go for the VALUE of those coins 25x + 10(x+138) + 5(2x) + 1(14x+28...
*April 11, 2016*

**Math**

total ages = 60 Generally, if the mode is 8 would mean there are more than one age of 8 suppose there are two with age 8, leaving 44 for the other 4 (11 for the average of the remaining 4) could have 9 and 13, and 8 and 14 so we could have: 8,8,8,9,13,14 or we could have: 8,8,...
*April 11, 2016*

**Calculus**

go to your other post further up
*April 11, 2016*

**Calculus**

at x = 5, we get 20/0 which is undefined The limit does not exist (we only have work to do if the limiting value produces 0/0)
*April 11, 2016*

**Math**

Haven't seen anybody use tables out of "handbooks" in over 30 years, .... amount = 9000(1.08^20 - 1)/.08 = 9000(45.7619643) ---> last number should be in your handbook = $411,857.68
*April 11, 2016*

**Math**

A blue car cannot be on either end. So we have to start and end with a red car. They must be parked this way RBRBRBR number of way to do this is R-B-R-B-R-B-R 4x3x3x2x2x1x1 = 144
*April 11, 2016*

**Word problem middle school**

This looks like a GP with a = 4 r = 1.5 so cost = 4 + 4(1.5) + 4(1.5)^2 = ... I will let you do the arithmetic
*April 11, 2016*

**Bus. Math help!**

So PV = 80,000 i = .085/12 = .0070833333.... n = 12(25) = 300 payment = x x(1 - 1.00708333..^-300)/.00708333...) = 80,000 x = 644.18 which is none of the choices, D would come closest
*April 11, 2016*

**probability**

let m be the mean, and let s be the standard deviation (11 - m)/s = -3 11-m = -3s (16-m)/s = 3 16-m = 3s add them : 27 - 2m=0 m = 13.5 3s = 16-13.5 = 2.5 Using my favourite normal distribution calculator: http://davidmlane.com/hyperstat/z_table.html I get .305
*April 11, 2016*

**Math**

C is correct
*April 11, 2016*

**Calc**

If (a,b) is a point not on Ax + By + C = 0 then the shortest distance D from (a,b) to the line is D = |aA + bB + C|/√(A^2 + B^2) First change your equation into general form: 4x - 2y - 4 = 0 D = |1(4) + (-5)(-2) - 4|/√(16+4) = 10/√20 = 10/2√5 = 5/√...
*April 11, 2016*

**Math**

I will go with your definitions then 2πr + 4s = 9 s = (9-2πr)/4 total area = A = πr^2 + s^2 = πr^2 + (9-2πr)^2 /16 dA/dr = 2πr + (1/8)(9-2πr)(-2π) = 2πr - π(9-2πr)/4 = 0 for a max/min 2πr = π(9-2πr)/4 8π...
*April 11, 2016*

**Math**

This question is not as easy as it first appears. John found the number of ways to select exactly 3 coins from the 5 given. But it said at least 3 coins so we could have 4 or all 5 number of ways to select = C(5,3) + C(5,4) + C(5,5) = 10 + 5 + 1 = 16 But we have not yet ...
*April 11, 2016*

**Algebra 2**

For each of the given trig ratios, make a sketch of the corresponding right-angled triangles sinα = 12/13 , so y = 12, r = 13 x^2 + y^2 = r^2 x^2 + 144 = 169 x^2 = 25 x = 5 in quad I , so sinα = 12/13 , cosα = 5/13 cosβ = 21/29 in quadrant I x = 21, r=29 y...
*April 11, 2016*

**math**

Just do it. The instructions are quite clear.
*April 11, 2016*

**algebra**

for y = ax^2 + bx + c the x of the vertex is -b/(2a) so for yours, the x of the vertex = 16/8 = 2 I see (2, -7) as the only point where x = 2 I would now sub x = 2 into the equation to make sure I get -7
*April 11, 2016*

**Algebra 2**

Steve, as long as they are not imaginary.
*April 11, 2016*

**math**

The letters: AA RR NN G EE M T Number of arrangements = 11!(2!2!2!2!) = 2,494,800
*April 11, 2016*

**math**

let the number of students be 19x let the number of teachers be x 19x + x = 500 20x = 500 x = 25 There are 19(25) or 475 students and 25 teachers check: total = 25+475 = 500 ratio = 475 : 25 = 19:1
*April 11, 2016*

**calculus**

h = -16t^2 + 79t + 4 we need the vertex of this downwards parabola the t of the vertex = -b/2a = -79/-32 = 79/32 sec for that time height = -16(79/32)^2 + (79/32)(79) + 4 = 197.796.. = 197.80 correct to 2 decimals check my arithmetic
*April 11, 2016*

**Math HELP PLEASE QUICK!**

3.54x10^7 m /(3x10^8 m/s) = .118 seconds
*April 11, 2016*

**Calculus**

I will assume that you had y'' = 2(x-12)/x^4 f(x) will be concave up when y" > 0 and concave down when y" < 0 we don't have to worry about x^4, it will always be positive, except when x = 0 , which is a restriction on f(x) anyway. I don't see ...
*April 11, 2016*

**Calculus**

f(x) = ax^3 + cx^2 + d f'(x) = 3ax^2 + 2cx + 0 f'(-4) = 9 48a - 8c = 9 ** the point (-4,9) is on f(x) -64a + 16c + 6 = 9 *** 2 times ** ---> 96a - 16c = 18 *** ---------> -64a + 16c = 3 add them: 32a = 21 a = 21/32 in 48a - 8c = 9 48(21/32) - 8c = 9 -8c = -45/2 c...
*April 11, 2016*

**mathematics-root of cubic eqn**

let f(x) = x^3 + 2x^2 + 3x - 4 by trial: attempt x = ±1 , ±2, ±4 f(1) = 1+2+3-4 ≠ 0 f(-1) = -1+2-3-4 ≠ 0 f(2) = 8+8+6-4 ≠ 0 f(-2) = -8 + 8 - 6 - 4 ≠ 0 f(4) ≠ 0 f(-4) = -64 + 32 - 12 - 4 ≠ 0 There are no nice rational ...
*April 11, 2016*

**Math**

The 300 would be correct if he gave no discount So his final selling price has to be P300 let the marked price be x so .6x = 300 x = 300/.6 = 500 check: the marked price is 500 giving a discount of 40%, which is 200 means that he sells at 300 profit = 300-200 = 100 percentage ...
*April 11, 2016*

**Math**

distance of 1st bounce --- 8 distance of 2nd bounce --- 2(4) = 8 distance of 3rd bounce --- 2(2) = 4 distance of 4th bounce --- 2(1) = 2 distance of 5th bounce --- 2(1/2) = 1 distance of 6th bounce --- 2(1/4) = 1/2 distance of 7th bounce --- 2(1/8) = 1/4 distance of 8th bounce...
*April 11, 2016*

**@ Anonymous**

If you are going to give a detailed solution, then you should not gloss over the critical part of your solution: SO Equation 1 X + (6/X) = 5 X=2 or else you might just as well state the obvious solution at the beginning.
*April 11, 2016*

**math**

2 and 3 just sort of popped into my mind.
*April 11, 2016*

**Math**

Your distance of 450.69 miles is correct However, the angle of 17.43 is the angle within the triangle. You must add the original direction of 27 degrees to get S 44.3 E
*April 11, 2016*

**Math**

After you make your sketch, and after you enter your angles, you should realize that the plane makes a 90 degree turn. So you just have a right-angled triangle. Use Pythagoras to find the distance. Let the angle opposite the 135 side be θ then tanθ = 135/430 θ...
*April 11, 2016*

**Math: Trigonometry**

ahhh, missed the part where we want the sum of the first 3 π/12 + 5π/12 + 7π/12 = 13π/12
*April 10, 2016*

**Math: Trigonometry**

4cos^2(2x-pi) = 3 cos^2 (2x - pi) = 3/4 cos (2x-pi) = ± √3/2 I know that cos 30° = √3/2 so 2x - pi = pi/6 2x = pi + pi/6 x = 7pi/12 ---->105° since we had cos(2x-pi) = ± √3/2 2x - pi could have been in any of the 4 quadrants 2x - pi...
*April 10, 2016*

**Geometry**

simplest way: Heron's Formula A = √(s(s-a)(s-b)(s-c)), where s = (1/2)the perimeter. s = (1/2)(15 + 15 + 8) = 19 s-a = 19-15 = 4 s-b = 19-15 = 4 s-c = 19-8 - 11 area = √(19(4)(4)(11) = √3344 = appr 57.83 2nd way: works in this case because it is isosceles...
*April 10, 2016*

**math**

First let's choose the books top shelf = C(6,4) = 15 middle shelf = C(3,2) = 3 bottom shelf = C(6,3) = 20 so he can read 15x3x20 or 900 different combinations of 9 books Now for each of the choices of 9 books, he can read them in 9! ways. so the number of ways he can read ...
*April 10, 2016*

**math**

ahh, behold the beauty of the metric system 130 mm = 13 cm
*April 10, 2016*

**Math**

Don't know what you mean by "I had to make prisms out of construction paper of the same size". Did you mean the same volume? , the same height? What stays the same?
*April 10, 2016*

**Trig**

you need to sketch right-angled triangles to get the missing sides given: sinx = -1/4, y = -1, r = 4 x^2 + y^2 = r^2 x^2 + 1 = 16 x = -√15 in III So sinx = -1/4 , cosx = -√15/4 , tanx = 1/√15 given: cosy = -4/5, x = -4, r = 5 then y = -3 siny = -3/5, cosy = -...
*April 10, 2016*

**algebra**

So this flagpole is almost 4 miles high? WOW And the cables are attached almost 2 miles from the base of this massive flagpole?? Check your typing, I bet you dropped a decimal point or something.
*April 10, 2016*

**Math**

Other than the fact that you can't bushwhack on the Appalachian Trail, we have a clear cut case of using the cosine law: let the distance back be x miles x^2 = 8^2 + 10^2 - 2(8)(10)cos113° = 273.40... x = 16.534.. (don't round off your calculator answer) now by the...
*April 10, 2016*

**Math**

#1, correct #2, to be horizontal, they must have the same y to be vertical, they must have the same x So, do you wish to change your answer?
*April 10, 2016*

**Math**

assuming that numbers and letters can be repeated ... number of cases = 26x10x10x10x26 =
*April 10, 2016*

**Trigonometry**

for each one, use the CAST rule to find where else a certain trig ratio is positive or negative for #1, you have found the angles in quadrant I, but the tangent is also positive in III, (the T of CAST) So è = 30 degrees in I ---> pi/6 or è = 210 in III ------ ...
*April 10, 2016*

**interest**

no time given for the first part. 2nd part: 500(1.04)^n = 1000 1.04^n = 2 take log of both sides n log 1.04 = log 2 n = log2/log1.04 = 17.67 years or n = 17.7 years correct to one decimal
*April 10, 2016*

**Geometry**

confusing question. Where does A come from. your 4 points R,S,T,U do not form a parallogram What are Rec1 etc ?
*April 10, 2016*

**math**

I know that Sixteen tons will get you another day older and deeper in debt
*April 10, 2016*

**Math**

Just did this less than an hour ago http://www.jiskha.com/display.cgi?id=1460275337
*April 10, 2016*

**Maths**

volume = pi r^2 h plug in your numbers, your r = .8
*April 10, 2016*

**Math**

a) for 25 therms cost = $.6686(25)) = $16.72 b) cost = 16.72 + (45-25)(.8587 = $33.89 c) cost = (x-25)(.8587) + 16.72 , for x > 25 or = .6686x , for 0 < x ≤ 25
*April 10, 2016*

**math**

morning of day 1 -- 3 ft evening of day 1 -- 1 ft ,(3-2) morning of day 2 -- 4 ft evening of day 2 -- 2 ... morning of day 27 -- 29 ft evening of day 27 -- 27 ft morning of day 28 -- 30 ft He has reached the top, no sliding back He will reach the top on Feb 28th
*April 10, 2016*