Wednesday

August 24, 2016
Total # Posts: 35,548

**Math**

grandma's age --- 10x + y mother's age ---- 10y + x one year ago: grandma : 10x+y - 1 mothers: 10y+x - 1 10x+y - 1 = 2(10y+x-1) 10x + y - 1 = 20y + 2x - 2 8x - 19y = -1 8x = 19y-1 x = (19y-1)/8 try different y's so that the numerator is a multiple of 8 e.g. when y...
*May 22, 2016*

**Pre-Calc**

Prob(3 or 4 are aces) = ( C(4,3)C(48,2) + C(4,4)C(48,1) )/ C(52,5) = ....
*May 22, 2016*

**Math**

Each pear costs $4 more than each Apple --- p = a + 4 Now , that's some expensive fruit !! 6a = 4p 6a = 4(a+4) 6a = 4a + 16 2a = 16 a = 8 , then p = 12 An apple costs $4 and a pear costs $12 WOW, but the answers check out for you info
*May 22, 2016*

**Math**

What is 4000(1.01025)^60 ?
*May 22, 2016*

**algebra**

Trying to make sense out of the gibberish English. I will assume you meant: How old will her daughter be when her age is 1/3 of her mother's age. daughter now : ---- 0 mother now -------21 0+x = (1/4)(21+x) 4x = 21 + x 3x = 21 x = 7 Find their ages in 7 years, and see if ...
*May 22, 2016*

**Math**

original numbers: x and y original product : xy new numbers: .75x and .5y new product = .375xy or (3/8)xy change in product = (5/8)xy percentage change = (5/8)xy/(xy) = 5/8 = .625 = 62.5 %
*May 22, 2016*

**Maths**

(3/4)x + (1/7)x + 27 = x times 28 21x + 4x + 756 = 28x at this point I can tell that he spent 25/28 of his money and he would have 3/28 of it left over 25x + 756 = 28x 3x = 756 x = 252 state you conclusions
*May 22, 2016*

**MATHS**

wouldn't that have to be 76479 ?
*May 22, 2016*

**Pre-Calc**

Prob(3 hearts) = C(13,3)/C(52,3) = 286/22100 = .0129 yes
*May 22, 2016*

**maths**

clock #1 runs at (29/30)t relative to real time clock #2 runs at (61/60)t relative to real time (61/60)t - (29/30)t = 10 times 60 61t - 58t = 600 3t = 600 t = 200 minutes or 3hours, and 20 minutes which would make it 9:30 am
*May 22, 2016*

**Mathematics**

(...7)(...7) ends in 9 (.....9)( .... 7) ends in 3
*May 22, 2016*

**Math**

Aaron ---- x his dad --- 9x One year ago: Aaron --- x-1 his dad --- 9x-1 9x-1 = 11(x-1) + 2 9x - 1 = 11x - 11 + 2 8 = 2x x = 4 Aaron is 4 dad is 36 one year ago Aaron -- 3 dad ---- 35 ---> was he 2 more than 11 times 3 ?? YES
*May 22, 2016*

**Math**

monthly rate = .0585/12 = .004875 outstanding balance = 22350(1.075) - 1200 = 22826.25 interest for 1st month = 22826.25(.004875) = 111.28 amount going to principal = 475.25 - 111.28 = $363.97
*May 21, 2016*

**math**

first piece ---- x 2nd piece ---- 12-x I will assume the second piece is 3/2 inches longer than the first piece 12-x - x = 3/2 12-2x = 3/2 24-4x = 6 4x = 18 x = 4.5 first piece is 4.5 2nd piece = 12-4.5 = 7.5 So, what do you think?
*May 21, 2016*

**Addition to .. - logarithm math-need help!!!!**

My equation near the end should have included: 5 log 4 x + 48log x 4 = x/8 5 log4 x + 48/log4 x = x/2 or 5log 4/log x + 48log x/log 4 = x/2 btw, that is what I used in Wolfram , so my answer stands as is
*May 21, 2016*

**logarithm math-need help!!!!**

5logxbase4+48log4basex=x/8 ---> 5 log 4 x + 48log x 4 = x/8 One of rules of logs: log a b = 1/log b a and furthermore: log a b = log b/log a so 5 log 4 x + 48log x 4 = x/8 I don't know of any nice method to solve this, I ran it through Wolfram and got x = 2130.13 , ...
*May 21, 2016*

**Math**

This same question was recently in the news http://www.iflscience.com/editors-blog/can-you-solve-math-problem-went-viral-japan the way it was written by Jerry the answer would be 9
*May 21, 2016*

**Algebra**

Since you are putting the marble back, the prob of the second event is the same as the first one. Prob(red,red) = (2/10(2/10) = 1/25
*May 20, 2016*

**math**

What is the meaning of the "x" between the two equations? is the second equation 3y = 13 ? Then y = 13/3, which does not show up in any of your choices.
*May 20, 2016*

**HELP ON MATHHHH!!!!**

I think you want something like 3x - 4 ≤ 15 then 3x ≤ 19 x ≤ 19/3 If this is what you meant then the values from your set that would work are: { 0, 3, 5, 6} Make suitable adjustments to my my solution of you meant something other than ≤
*May 20, 2016*

**Math Help!**

#1, correct #2. Volume of any solid that comes to a point: V = (1/3) base x height = (1/3)(24^2)(24) = 1/3(24^3 = 4608
*May 20, 2016*

**nawal**

You should make a point to memorize the ratio of sides of the 30-60-90° triangle, which is 1 : √3 : 2 so for yours: √3/1 = √6/x √3x = √6 x = √2 then the hypotenuse = 2√2 area = (1/2)base x height =(1/2)(√2)(√6) = (1/2...
*May 20, 2016*

**math**

Just set up a simple ratio: 60/1.5 = 100/t
*May 20, 2016*

**math**

nothing found in the coefficients. for the m's --- > m^6 for the n's ----> n so GCF = m^6 n
*May 19, 2016*

**Math Trigonometry**

I made a sketch with Chicago as C, A as the end of the first flight, and B as the end of the 2nd flight. In triangle ABC AC = x, AB = 150, BC = 195, angle A = 65° by the sine law: sinC/150 = sin 65/195 sinC = .69715... C = 44.199... (I stored that in calculator's ...
*May 19, 2016*

**math**

Did you not read Steve's answer to your previous question regarding the condition to have a triangle? http://www.jiskha.com/display.cgi?id=1463702386
*May 19, 2016*

**Algebra**

number of .15 increases ----- n price per bushel = 5 + .15n number of bushels sold = 1000 - 10n income = (5+.15n)(1000 - 10n)
*May 19, 2016*

**math**

yes
*May 19, 2016*

**math**

let each of the straights be x m then the perimeter is 2x + 2half-circles = 2x + circumference of 1 circle 2x + 2π(35) = 400 solve for x
*May 19, 2016*

**College Algebra**

pounds of $8 nuts ----- x pounds of other nuts ---- 41-x 8x + 2(41-x) = 7(41) solve for x
*May 19, 2016*

**Math**

2^x=17 take log of both sides, then use log rules x log2 = log 17 x = log17/log2 = appr 4.087 4log4^(x)=7 log 4^x = 1.75 4^x = 10^1.75 4^x = 56.23413... repeat the same steps I used in the first one to finish it
*May 19, 2016*

**Algebra 2**

find the z-score for 140, then use your tables or charts or some software to find that .1587 will pass so number of the 360 that will pass = .1587(360) = 57 rounded to the nearest person
*May 19, 2016*

**Trig**

If sinØ = 3/7, y=3 , r = 7 and x^2 + 3^2 = 7^2 x = ± √40 Ø could be in I or II if Ø is in I sinØ = 3/7 cosØ = √40/7 cos(π/2 - Ø) = cos π/2 cosØ + sin π/2 sinØ = 0 + sinØ = 3/7 If &...
*May 19, 2016*

**Algebra**

y = -2/5x + 3 multiply each term by 5 , the LCD 5y = -2x + 15 get the x's and y's to one side, the constant to the other 2x + 5y = 15 None of your choices are correct. e.g. for y = (-2/5)x + 3 , (the original) the y-intercept is (0,3) (0,3) does not satisfy any of the ...
*May 19, 2016*

**math**

Assuming the 2 bags are distinguishable. then : C(5,1)xC(4,4) + C(5,2)xC(3,3) + C(5,3)xC(2,2) + C(5,4)xC(1,1) = 5 + 10 + 10 + 5 = 30 notice that this is row 1 5 10 10 5 1 of Pascal's triangle with out the leading and ending 1's. If the 2 bags are indistinguishable, ...
*May 19, 2016*

**algebra 1**

You want to find: −16t^2 + 90t + 50 = 28 + 48.8t 16t^2 -41.2t - 22 = 0 by the formula: t = (41.2 ± √3105.44)/32 = appr 3.03 or -.454 so you are correct, it is between 3 and 4, much closer to 3 seconds
*May 19, 2016*

**Math**

Flaw in problem: Two persons mentioned, but 3 terms in the ratio
*May 19, 2016*

**Calculus**

The way you worded the question, "How quickly is it moving away from the observer at that moment" , implies to find the rate at which the distance between the balloon and the observer changes. So we could just use Pythagoras after t sec, height of balloon is 8t ft so...
*May 18, 2016*

**Algebra 2**

I have to know more about the spinner. How many colours, etc
*May 18, 2016*

**Algebra**

nope, it is 4 units up Make a table of values of each using the same x's and see what happens http://www.wolframalpha.com/input/?i=plot+y%3D+-6+x%5E2+%2B4+,+y%3D+-6x%5E2
*May 18, 2016*

**alg 2**

the centre of (x - 2)^2 + (y + 1)^2 = 16 is (2,-1) Now move that centre 4 units to the left and 6 units up New centre is ....... new equation is .......
*May 18, 2016*

**Calculus**

a = 1.1+2(t^1/2) v = 1.1t + (2/(3/2)) t^(3/2) + c v = 1.1t + (4/3)t^(3/2) + c when t = 0 , v = 0 0 = 0 + 0 + c -----> c = 0 v = 1.1t + (4/3) t^(3/2) when t = 9 v = 1.1(9) + (4/3) (9)^(3/2) = 9.9 + (4/3)(27) = 9.9 +36 = 45.9 m/h
*May 18, 2016*

**math**

expression "2n+1" is your "number pattern" what do you get when you plug in n = 1, 2, 3, ... ?
*May 18, 2016*

**gscc**

height of cone is 1/2 the diameter ---> height of cone equals its radius V= (1/3)π r^2 h, but r = h V = (1/3) π h^3 dV/dt = π h^2 dh/dt *** dV/dt = 200 cm^3/s so when t = 10 V = 2000 cm^3 2000 = (1/3)π h^3 h^3 = 6000/π h = (6000/π)^(1/3) = appr...
*May 18, 2016*

**math**

4^x = 2^(2x) = (2^x)^2 let y = 2^x , so your equation becomes y^2 - 9y = -20 y^2 - 9y + 20 = 0 (y-4)(y-5) = 0 y = 4 or y = 5 then 2^x = 4 = 2^2 x = 2 or 2^x = 5 take log of both sides, and use log rules x log2 = log5 x = log5/log2 = appr 2.322
*May 18, 2016*

**Math**

20 evens, and 20 odds prob(E,E) = (20/40)(19/39) = 19/78
*May 18, 2016*

**Inequality**

-2 < 7-3x ≤ 10 subtract 7 from everybody -9 < -3x ≤ 3 divide everybody by -3, must switch inequality sign 3 > x ≥ -1 -1 ≤ x < 3 so integral values are {-1, 0, 1, 2}
*May 18, 2016*

**Math**

Wow, I don't see a single one of your answers. How can I possibly check them?
*May 18, 2016*

**Math**

To have the same colour, you need either BBB or RRR Find the prob of each case, then add them up
*May 18, 2016*

**Math**

If passing math depends on this ONE question, and you don't know how to answer this simple question, I don't think you should pass.
*May 18, 2016*

**Math**

prob(at least 1 boy of 4 kids) = 1 - prob(all girls) = 1 - (1/2)^4 = 1 - 1/16 = 15/16
*May 18, 2016*

**Math/Applied**

For the sum to be odd, one choice must be even , the other odd (the sum of two odds is even, the sum of 2 evens is even) We have 5 odds and 4 evens in the bag so 2 cases: prob(E, then O) = (4/9)(5/8) = 20/72 = 5/18 prob(O, then E) = (5/9)(4/8) = 5/18 prob(your event) = 5/18+5/...
*May 18, 2016*

**Math**

missing 3 times out of how many tries?? if prob(miss out of 3 tries) = (1/10)^3 = 1/1000
*May 18, 2016*

**Math**

looks like somebody has some major studying ahead of them
*May 18, 2016*

**Math**

I copied your post with only those that are INCORRECT I am using <-------- to show the correct answer 1. Simplify. 3x^2+ 5x-5x^2-4x+5-2 A.-8x^2-9x+3 B.2x^2+x+3 C.-2x^2-9x+3*** D.-2x^2+x+3 <--------- 4.The distance from Newtown to Old town on the highway is (6x^2 + 2x &#...
*May 18, 2016*

**Math**

Any reason why you are capitalizing every word? Assuming your garbled last sentence is something like: "If one of the sides of the first triangle is 6 cm, what is the length of the corresponding side of the second triangle ? " Areas of similar triangles are ...
*May 18, 2016*

**Differential Calculus**

Make a sketch of the cone with some water in it. Let the depth of the water be h ft, and the radius of the water level be r ft by similar triangles: r/h = 3.75/15 3.75h = 15r h = 4r or r = h/4 V = (1/3)π r^2 h V = (1/3)π(h^2/16)h V = (1/48)π h^3 dV/dt = (1/16)&#...
*May 18, 2016*

**Calculus**

take the 2nd derivative, set it equal to zero and solve for x that will be the x value of the inflection point, sub it back into the original equation to get the y your second derivative will be a linear expression, thus easy to solve for x
*May 18, 2016*

**Math**

you have 6 pizzas, and you slice each one of them into 5 pieces. How many pieces will there be in total ?
*May 18, 2016*

**math**

Find the area of the rectangle. Find the area of the circle take the difference between the two answers.
*May 18, 2016*

**financial management**

i = .16/12 = .013333... p(1 - (1.013333..)^-12)/.01333.. = 250000 solve for p , where p is the monthly installment
*May 18, 2016*

**Math**

area of parallogram = base x heigh = 6.5(4.8) = .. new dimension: base = 13 height = 6.3 new area = 13(6.3) = .... take the difference
*May 17, 2016*

**Algebra**

y = kx plug in the given values of x and y, then solve for k rewrite the original equation, now that you know k
*May 17, 2016*

**math**

(1/2)(l) = 2/3 l = (2/3) ÷ (1/2)
*May 17, 2016*

**math**

(sum of 4 tests + x)/5 = 77
*May 17, 2016*

**Math3(Reiny Please Help)**

h(t) - -9.81t^2 + 0t + h = 0 when it hits the ground when t = 3.5 -9.81(3.5)^2 + h =0 h = 120.1758 m b) repeat for the equation h(t) = -9.81t^2 -5t + 120.1725 set that equal to 0 and solve for t , reject any negative values of t
*May 17, 2016*

**Math2(Reiny Please Help)**

set 0.02(3s^2 + 20s) = 50 3s^2 + 20s = 2500 3s^2 + 20s - 2500 = 0 Use the quadratic formula, reject the negative answer.
*May 17, 2016*

**Math(Reiny Please Help)**

let the width against the barn be x ft let the length parallel to the barn be y ft so total length = 600/15 = 40 so she needs to fence 40 ft 2x + y = 40 y = 40-2x area =xy = x(40-2x) = 40x - 2x^2 are you taking Calculus? if so, d(area)/dx = 40 - 4x = 0 for a max of area x = 10...
*May 17, 2016*

**Math**

a) number greater than 9: 10,11,12,13,14,15 so 6 of them prob(as stated) = 9/15 = 3/5 b) do it the same way, count how many are prime, and how many are composite
*May 17, 2016*

**Math**

areas of similar figures are proportional to the square of their corresponding sides so the larger one is 9 times as large, or 243 m^2 or, if you didn't know that property let the original be (1/2)(base)(height) = 27 new one is (1/2) (3base)(3height) = 9 (1/2)(base)(height...
*May 17, 2016*

**MATH**

of course! you must have the same units 12/9 would be a meaningless calculation. 36 ft ÷ (9/12) ft = 48 Now, the question is not clear about posts at the end. e.g. If the fence has one side along a house, would you need a post right against the house at each end? If so ...
*May 17, 2016*

**math**

term5 = a+4d term2 = a+d a+4d = 2(a+d) a+4d = 2a + 2d a = 2d sum(20) = 10(2a + 19d) = 1150 2a + 19d = 115 4d+19d=115 23d = 115 d = 5 a = 10 you MUST know how to do this simple kind of question. Repeat the solution on your own, without looking at mine. Practise, practise, ...
*May 17, 2016*

**math**

volume of well = π r^2 h = π(7^2)(20) = 98π m^3 surface area to be covered by dirt = 100(42) - π(7^2) =4200 - 49π m^2 let the depth of the dirt be h m (4200 - 49π)h = 98π check and do my arithmetic
*May 17, 2016*

**Math**

What is your choice ?
*May 17, 2016*

**Math**

If expressed in terms of y ... 4y = 2x y = (2/4)x = (1/2)x so yes, with k = 1/2
*May 17, 2016*

**Math/algebra**

- find the mean - take the difference between each of your data values and the mean - square each of these differences - add up these squares of differences - divide by 10 - take the square root I will not do the arithmetic of that for you
*May 17, 2016*

**Math/algebra**

you have a GP, with a = -2, r = -2 term(20) = a r^19 = -2(-2)^19 = (-2)^20 = 2^20 = 1,048,576
*May 17, 2016*

**Math Help Please I Don't Understand**

you have to be familiar with the meaning of the constants in an equation such as y = a sin k(Ø+d) + c a is the amplitude, our range of heights is 60 ft so a = 30 y = 30sin kt + c , where t is in minutes the lowest value so far would be -30, but we need our lowest to be...
*May 17, 2016*

**Geometry**

So you want them to be an arithmetic sequence 19 , 19+d, 19+2d, 19+3d but 19+3d = 55 3d= 36 d = 12 etc
*May 17, 2016*

**MATH**

Let the width be w area of first = 12w area of 2nd = 8w 12w - 8w = 320 carry on
*May 17, 2016*

**math**

I noticed that Steve answered this for you 20 minutes ago. Why are you repeating it ?
*May 17, 2016*

**Algebra**

The way you typed it, it would be undefined for x = 0 if you meant: (x+1)(x-2)/(x^2-25) then it would be undefined for x = ± 5
*May 16, 2016*

**Algebra**

so your height formula is h = -4.9t^2 + 4.9t + 0 , assuming kicked from ground when it lands, h = 0 -4.9t^2 + 4.9t = 0 -4.9t(t - 1) = 0 t = 0 ----> at the moment the ball is kicked or t = 1, it lands 1 second later
*May 16, 2016*

**Finance**

This is a normal amount of annuity problem payment = 650 i = .078/4 = .0195 n = 4(5) = 20 amount = 650 ( 1.0195^20 - 1)/.0195 = $15,714.90
*May 16, 2016*

**math**

you will be in the 4th quadrant, 39° down from the x-axis cos 39° = x/800 x = 800cos39 = 621.7 m east y = 800sin39 = 503.5 m south notice : 621.7^2 + 503.5^2 = 639979.1489 √639979.1489 = 799.987 , not bad
*May 16, 2016*

**Math**

y^2 + 9y + 9 = 0 straightforward quadratic equation, unfortunately it does not factor, so .... by the formula y = (-9 ± √45)/2
*May 16, 2016*

**Math(Reiny Could You Help?)**

the vertex of f(x) is (2,9) The vertex of g(x) is to the right 2 units and 5 units down, so its vertex must be (4,4) since the "shape" has to be the same, we need the same 3 in front so g(x) = 3(x-4)^2 + 4 domain: the set of real numbers range: y ≥ 4 , since ...
*May 16, 2016*

**Math**

golf balls ---- 20x tennis balls -- 5x 20x+5x = 100 25x = 100 x = 4 so 80 golf balls and 20 tennis balls
*May 16, 2016*

**Geometry**

slope of AB = (4+8)/(-9+7) = 12/-2 = -6 so the slope of the perpendicular = 1/6 midpoint of AB = (-8,-2) equation of our line: y + 2 = (1/6)(x+8) 6y + 12 = x+8 x - 6y = 4
*May 16, 2016*

**math**

We clearly need a diagram to know what you are talking about. Since we cannot post diagrams here, ......
*May 16, 2016*

**Math**

your function is modelled by a parabola which opens downwards. when the package reaches the water, h(t) = 0 -4.9t^2 + 10t + 1200 = 0 t = (-10 ± √23620)/-9.8 = -14.662 or 16.7029 We will reject the negative time, so it took appr 16.7 seconds for the package to ...
*May 16, 2016*

**Math (Trig)**

you know that the point is in quad II and tanØ = 2/-1 I know that for tanØ= +2, Ø = appr 1.107 so our angle in II is Ø = π-1.107 = 2.0344 so it has to be (5, 2.0344) if you use the form (r,Ø)
*May 16, 2016*

**Math**

I don't like the wording "repeatedly" Usually this type of question uses "continuously" to describe the increase. amount = a e^(kt) , where k is the annual rate , t is the time in years and a is the initial amount. e^(k(9.25)) = 2 take ln of both sides ...
*May 16, 2016*

**math**

A not-so-subtle way to promote two wineries??
*May 16, 2016*

**Calculus**

We need their intersection: 2x^2 - 2 = x^2 + 1 x^2 = 3 x = ± √3 we want only the part in the first quadrant effective height = x^2 + 1 - (2x^2 - 2) = 3 - x^2 area = ∫(3 - x^2) dx from 0 to √3 = [3x - (1/3)x^3] from 0 to √3 = 3√3 - (1/3)(3&#...
*May 16, 2016*

**Math**

h(t) = -4sin (π/4)(t-1)+2.5 The period of this function is 2π/(π/4) = 8 So we want to see where the sine curve falls below the x-axis for 3 periods of the curve, starting at t=0 0 = -4sin (π/4)(t-1)+2.5 4sin (π/4)(t-1) = 2.5 sin (π/4)(t-1) = .625 ...
*May 16, 2016*

**math**

f+k = 1548 f+j = 1842 subtract those two equations: j-k = 294 j = 294 + k k/j = 4/7 4j = 7k j = 7k/4 sub into j = 294+k 7k/4 = 294 + k times 4 7k = 1176 + 4k 3k=1176 k = 392 then j = (7/4)(392) = 686 f+j = 1842 f = 1156
*May 16, 2016*

**math**

227.5( 1- (1+i)^-60)/i = 9500 You will need some "fancy" methods to solve this type of an equation, e.g. Newton's Method I just ran it through Wolfram and got i = .0127495 for a monthly rate or an annual rate of appr . .152994 or appr 15.3% per annum compounded ...
*May 16, 2016*

**Statistics**

I assumed you know how to find the mean and sd for the given information.
*May 15, 2016*

**Statistics**

straightforward .... find z scores for both 12 and 14 minutes go to the chart, look up the two z-scores proabilities, then subtract them
*May 15, 2016*