Monday

September 26, 2016
Total # Posts: 36,030

**math**

larger or small ---- 2 from 4 colours ---- 4 from 3 ribbons --- 3 number of ways to choose a balloon = 2*4*3 = 24

*May 6, 2016*

**Math**

multiply the first by 4 4x-12y = 4 4x + 5y = 4 subtract them: -17u = 0 y = 0 back into the first: x - 0 = 1 x = 1

*May 6, 2016*

**Algebra**

amount = 64(1/2)^(t/10) , where t is in minutes, and amount is in g. sub in t = 20

*May 6, 2016*

**math**

What made you "sure" it was B or C ? Did you perform a long algebraic or synthetic division??

*May 6, 2016*

**Math CHECK MY ANSWER**

Without even reading the question, I would have ruled out your choice as the only one it could NOT be, since the probability of any even has to be a number between 0 and 1, and 12/5 > 1 There are 12 letters listed, 5 of them are vowels so prob(a vowel) = 5/12

*May 6, 2016*

**maths**

14 men dig 10 metres in 6 days 1 man digs 10/14 m in 6 days 12 men dig 10/14(12) m in 6 days, or 12 men dig 60/7 m in 6 days 12 men dig 1 metre in 6÷(60/7) day, or 12 men dig 1 metre in 7/10 days 12 men dig 15 metres in (7/10)(15) days 12 men dig 15 metres in 10.5 days

*May 6, 2016*

**Math**

make your sketch, to see a triangle with sides 5 and 7 and the contained angle of 108° by the cosine law: AC^2 = 5^2 + 7^2 - 2(5)(7)cos108 = 95.6311... AC = √95.6311.. = 9.778... (I stored that in memory) by sine law: sinØ/7 = sin108/9.778.. sinØ = ....

*May 6, 2016*

**math**

interest for first 40 days = 8500(40/365)(.06) = $55.89 total owing at that time =$ 8555.89 makes payment of $2000 Balance remaining = 6555.89 interest for next 70 days = 6555.89(70/365)(.06) = 75.44 total owing at that time = 6631.33 makes payment of $2000, leaving a balance ...

*May 6, 2016*

**Geometry**

number of triples from 10 = C(10,3) = 120 the triple of Rutgers, Miami, and Clemson is specifically one of those prob(your event) = 1/120

*May 6, 2016*

**Math**

almost, you are showing the division the wrong way 2 L = 2000 ml 2000 ml/14 glasses = 142 6/7 ml per glass that means 142 ml will be in each glass (the equal amount part of the question) with 6/7 of the divisor of 14 left over which would be 12 ml left over check: so each ...

*May 6, 2016*

**math**

So first you want to know how many pairs I can form from the 7 horses , then arranging the other 5 That would be C(7,2) or 21 for the first part - the remaining 5 horses can be arranged in 5! or 120 ways So there are 21(120) or 2520 ways to finish the race

*May 6, 2016*

**math**

games won by Lee --- 15 games won by ---- 2(15) + 3 = 33 total games = 48 prob(Tasha wins) = 33/48 = 11/16

*May 5, 2016*

**Math**

h^2 = 5^2 + 6^2 = 61 h = √61 = .....

*May 5, 2016*

**Trigonomentry**

Steve did this for earlier http://www.jiskha.com/display.cgi?id=1462459298

*May 5, 2016*

**Algebra**

Did you switch names? http://www.wolframalpha.com/input/?i=xy-x%2By%3D0

*May 5, 2016*

**math**

use your definitions fourth term = ar^3 = 9(-1/3)^3 = 9(-1/27) = -1/3 or simply list the first 4 terms to see the 4th term 9, -3, 1, -1/3, ...

*May 5, 2016*

**Algebra**

before you even start, did you notice the two equations have the same slope, but have different y-intercepts. Thus they will never meet, and therefore there can't be a solution. If you try it anyway .... first equation: y = 2x+3 sub in the second 2x-2 = 2x + 3 -2= 3 , ...

*May 5, 2016*

**math- geometry**

Correct me if I am wrong in the understanding of the question. Round table, we don't know its radius, I eventually let it be r Smaller circle lies on the table, the radius of the smaller table is 1/2 or .5 m The area outside the circle is shaded and you said the area of ...

*May 5, 2016*

**math- geometry**

You started well , but it collapsed on you in the second part. I would not have rounded off intermediate answer, only round off your final answer. I assume you used a calculator, get into the habit of using the memories of the calculator to store intermediate answers. for area...

*May 5, 2016*

**math**

-2 9 -1 4 0 -1 1 -6 2 -11 looks like we are dropping the y by 5 for each increase of 1 in the x y = -5x - 1 , ----> I noticed that (0,-1) was the y-intercept

*May 5, 2016*

**Math**

find all pairs of factors of 72 72 = 1 x 72 = 2 x 36 = 3 x 24 = .... etc count them up, but I would not count the duplicates such as .... 24 x 3 36 x 2 72 x 1

*May 5, 2016*

**Math**

let the other side be x case 1: x/3.7 = 1.618 x = = 5.9866 or 6.0 inches to the nearest tenth case 2: 3.7/x = 1.618 x = 3.7/1.618 = 2.286.. or appr 2.3 inches

*May 5, 2016*

**math 21**

What is your question? the graph looks like this http://www.wolframalpha.com/input/?i=xy-x%2By%3D0

*May 5, 2016*

**math**

a^5/a^3 = a^2 x^9/x^5 = x^4 you do the others by simply using the division rule of powers.

*May 5, 2016*

**math**

yes check it by taking 1.8% of it

*May 5, 2016*

**math**

.018x = 72 solve for x

*May 5, 2016*

**MATH HELP PLZ!**

looks like the same as this http://www.jiskha.com/display.cgi?id=1462291500

*May 5, 2016*

**math**

earning in first year --- x earining in 2nd year = 5.5x earning in 3rd year = 5.5^2 x earning in 4th year = 5.5^3 x x(1 + 5.5 + 5.5^2 + 5.5^3) = 29250 inside the bracket is a GP, but since there are only 4 times, we might as well just add them up x(203.125) = 29250 x = 144 so ...

*May 5, 2016*

**math**

neighbour's age --- x (4x+7)/3 - 9 = 20 times 3 4x+7 - 27 = 60 4x = 80 x=20 The neighbour is 20 years old check: times 4 --->80 add 7 ---->87 divide by 3 --> 29 subtract 9 ---> 20

*May 5, 2016*

**Geography**

20°N, 80°E ----> right smack in the middle of India 20°S, 80° E --> you better be in a boat

*May 5, 2016*

**Math**

Confusing wording: "he first pyramid has a height of 6 inches and a base area of 10 inches" since you tell us the volume is 20 inches^2 , the base are must be 10 inches^2 I also will assume that the base does not change volume of 1st pyramid = (1/3)(10)(6) = 20 ...

*May 5, 2016*

**math**

The first 3 are correct. You check by making sure you subbed correctly in the formula and performed the arithmetic correctly. For the last one about Lucia I have no idea since we can't see your diagram.

*May 5, 2016*

**math**

whole circumference = 12π so your arc is 105/360 or 7/24 of that

*May 5, 2016*

**Algebra**

amount of cheaper mix --- x kg amount of expensive mix -- 18-x solve for x and sub into my definitions 5x + 10(18-x) = 7(18)

*May 5, 2016*

**Math ---HELP!!!!!**

I got .1587, which matches 16% or D Did you take 1 - ...., since it asked for "above" ?

*May 5, 2016*

**Math ---HELP!!!!!**

I got .6538 , so yours is close enough

*May 5, 2016*

**Math ---HELP!!!!!**

according to the chart I am using, I ge 43.26 , so I agree with your choice

*May 5, 2016*

**math**

Billions and billions of them ... here are just two of them: (0,-3) , (75.2 , 147.4)

*May 5, 2016*

**math**

base --- b height = b+5 (1/2)(b)(b+5) = 45 b^2 + 5b = 90 b^2 + 5b - 90 = 0 b = (-5 ±√385)/2 = appr 7.311 or some negative base = 7.311 , height = 12.311 check area = (1/2)(7.311)(12.311) = 45.0028.. not bad, my answer is correct

*May 5, 2016*

**Math**

I pasted your original post, so I don't have to scroll up and down. I have inserted the corrections. If nothing is shown , then the question was correct 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 ****** 3x^2+ 5x-5x^2-4x+5-2 = -2x^...

*May 5, 2016*

**Math**

do you not have a calculator? just watch the order of operation, should be [2cos(45)] - [tan(45)/90.5] - 64

*May 5, 2016*

**math**

Just translate into Math using your definitions of an AP a+5d = 7 ** a+ 3d = 2(a+d) - 1 a + 3d = 2a + 2d - 1 -a + d = -1 *** add ** and *** 6d = 6 d = 1 back in ** a + 5=7 a = 2 the first term is 2 check: sequence is 2,3,4,5,6,7,8, ... Is the fourth term less than twice the ...

*May 5, 2016*

**error in data - Trigonometry**

error in data if B is in quad III, then cosB must be negative I will assume you meant: cos B = -12/13 make sketches of triangles in the two quadrants for sinA = 1/2, y = 1, r = 2 x^2 + 1^2 = 2^2 x = √3 so tanA = y/x = 1/√3 for cosB = -12/13 in III x = -12 , r = 13 ...

*May 5, 2016*

**Math**

I assumed you made a sketch. On mine, I labeled the position of Ms Hunt as H on top of the tall building, its base J For the shorter building, I labeled its top as P and its bottom as Q I drew a horizontal from H to meet QP extended at R All kinds of right-angled triangles! ...

*May 5, 2016*

**Math**

you will need the vertex of this parabola the x of the vertex is -b/2a = 192.1/32.4 = 5.929 so add 5.9 or appr 6 years to 1925 to get the year 1931

*May 4, 2016*

**algebra**

x+y=4 or y = 4-x , and xy=6 sub in the first part x(4-x) = 6 4x - x^2 - 6 = 0 x^2 - 4x + 6 = 0 x = (4 ± √-8)/2 = 2 ± √2 If you are dealing with real numbers, there are no numbers to fit your condition. If you allow complex numbers, the two numbers are...

*May 4, 2016*

**Math**

I answered it in your previous post of this question

*May 4, 2016*

**Math**

let the number of chairs over 400 be x now: number of chairs = 400 price per chair = 120 Revenue = 48000 after production increase: number of chairs = 400+x price per chair = 120 - .25x Revenue = R = (400+x)(120-.25x) = 48000 + 20x - .25x^2 which is a downwards opening ...

*May 4, 2016*

**math**

log(2+x)-log(x-3)=log2 log( (2+x)/(x-3) ) = log2 "unlog" it (2+x)/(x-3) = 2 2x - 6 = 2+x x = 8 check it with your calculator

*May 4, 2016*

**Math**

correct

*May 4, 2016*

**Math**

correct, I use http://davidmlane.com/normal.html

*May 4, 2016*

**Math**

I used the actual normal distribution and got .9973 http://davidmlane.com/normal.html

*May 4, 2016*

**Math**

I used the actual normal distribution and got .9973 http://davidmlane.com/normal.html

*May 4, 2016*

**Math**

the largest rectangle would be the square 2W + 2L = 8 W+L=4 for a square each side is 2 cm, and the maximum area is 4 cm^2 There is no such thing as a smallest rectangle. We can make one of the sides very very small, but there would still be an area. e.g. suppose W = .001 then...

*May 4, 2016*

**math**

Since it asked for an estimate and and Dπ = C I would approximate 270/3 = 90 so the diameter is about 90, making the radius about 45 Since they wanted an estimated answer, giving answers with those kind of decimals makes no sense. Using 3.14 for π is not estimating.

*May 4, 2016*

**math**

Unfinished sentence .... Does your keyboard not have any capital letters? Whatever is missing in your sentence , the probability is 1/9

*May 4, 2016*

**Geometric Sequence**

you want: .95^n = .25 take log of both sides nlog.95 = log.25 n = log.25/log.95 = 27.0268.. = appr 27 washings or start with 100% colour after 1 washing ---- 95% left after 2 washings --- .95(.95) left after 3 washings --- .95(.95)^2 left .... after n washings ------ .95(.95)(...

*May 4, 2016*

**Maths**

boys --- b girls --- g b+g = 150 (3/4)b = (1/7)g 3b/4 = g/7 4g = 21b g = 21b/4 sub into the first b+g = 150 b + 21b/4 = 150 times 4 4b + 21b = 600 25b=600 b = 24 then g = 21(24/4) = 126 24 boys and 126 girls went to the concert check: is 24+126 = 150 ? , YES is (3/4)(24) = (1/...

*May 4, 2016*

**Algebra**

number of adult tickets ---- x number of children tickets -- 2000-x solve: 4x + 2(2000-x) = 6400 solve the value of x into my definitions

*May 4, 2016*

**math**

i = .0475/12 = .00395833.. n = 12(10) = 120 PV = 20,000(1.00395833..)^-120 = $12,449.37

*May 4, 2016*

**math**

Formulas are equations that contain an = sign you have an expression, not an equation, so... ???

*May 4, 2016*

**PLEASE HELP ASAP ALGEBRA**

Yes, 3 numbers are divisible by 3 so prob = 3/10

*May 3, 2016*

**mathematics**

GP ar^2 = 4a ----> r^2 = 4 r = ±2 ar^5 = 3ar^3 + 32 if r = +2 32a = 24a + 32 8a =32 a = 4 the sequence is 4,8,16,32,64, 128, ... if r = -2 -32a = -24a + 32 -8a = 32 a = -4 the sequence is -4, 8, -16, 32, -64, 128, ...

*May 3, 2016*

**Calculus 3**

starting with the 4th term, we have a definite pattern and the general term from that point is 1/(3^n + √(n+1) ) , where n starts with 1 Since you wanted to "write the series", why don't we just add the first 3 terms and begin the serious stuff with term 4 ...

*May 3, 2016*

**MATH**

let the number of gigs used be g Runfast: cost = 25 + 10g BA&D: cost = 18+15g let's see for how many g's the plans are the same cost of one = cost of the other 18+15g = 25+10g 5g = 7 g = 7/5 = 1.4 gigs so for 0 gigs over, BA&D would cost $18 vs $25 for Runfast, so BA&D...

*May 3, 2016*

**Analytic Geometry**

http://www.wolframalpha.com/input/?i=plot+x%5E2-xy%2By%5E2-3%3D0 nice rotated ellipse. This is a good equation for you to use in studying or reviewing the topic of rotation of conics. Obviously I could not possible teach you that on here in one post. When I last taught this ...

*May 3, 2016*

**calculus**

Sketch a right angles triangle with a base of 400 m, a height of h m , (the balloon), and an angle of Ø opposite the height. tan Ø = h/400 h = 400 tanØ dh/dt = 400 sec^2 Ø (dØ/dt) given: when Ø = 10° or 10(π/180) radians d&...

*May 3, 2016*

**math 1324**

Solve using matrices ??? What can be easier than the following? : amount borrowed at 9.5% ---- x amount borrowed at 8.5% ---- 4x amount borrowed at 7% = 2,000,000 - 5x .095x + .085(4x) + .07(2000000-5x) = 169750 solve for x , and sub back in my definitions

*May 3, 2016*

**Analytic Geometry**

factor it y(x+1) = x y = x/(x+1) a rotated hyperbola , with asymptote at x = -1 http://www.wolframalpha.com/input/?i=plot+y+%3D+x%2F(x%2B1)

*May 3, 2016*

**Maths**

So it would take 20 man-hours to paint the house, (or "person-hours to be politically correct) No distribute those 20 hours needed among 3 painters, so it would take 20/3 hours = 6 2/3 hours = 6 hours and 40 minutes

*May 3, 2016*

**Nath**

work backwards, 2:30 pm ---- 44° noon -------- 41° 7:00 am ----- 29°

*May 3, 2016*

**math**

So many questions: are the circles touching each other? are the circles the same size ? are each of the circles touching the length and width of the rectangle? ... etc

*May 3, 2016*

**Math**

If you want L/hr, then rate = (4/5) / (1/4) L/h = (4/5)(4/1) L/h = 16/5 L/h Daniel is correct

*May 2, 2016*

**Yup! - Math**

-- stands in corner with dunce cap --- looks like I had another "old-timer's " moment.

*May 2, 2016*

**Math**

I would have it as 90° < d < 180° think of it as: d is between 90 and 180

*May 2, 2016*

**Pre-calculus**

width = 8.5-2x length = 11 - 2x height = x V = x(8.5-2x)(11-2x) domain: 0 < x < 4.25

*May 2, 2016*

**correction - math**

use A^3 + B^3 = (A+B)(A^2 - AB + B^2) (memorize it) We call it the sum of cubes, we can also factor the difference of cubes. 8x^3 is a perfect cube and so is 1, so the expression fits the formula 8x^3+ 1 = (2x + 1)(4x^2 - 2x + 1)

*May 2, 2016*

**algebra**

first speed --- x mph return speed -- x+16 mph 6/x + 6/(x+16) = 1 times each term by x(x+16) 6(x+16) + 6x = x(x+16) x^2 + 4x - 96 = 0 (x-8)(x+12) = 0 x = 8 or x is a negative her first speed was 8 mph her return speed was 24 mph check: 6/8 + 6/24 = 1 , that's good!

*May 2, 2016*

**Math**

smallest angle --- x the other is ------ x+45 third ------ 2x - 5 solve for x: x + x+45 + 2x-5 = 180

*May 2, 2016*

**Trigonometry**

easier than it looks: cos^-1(radical3/2), means you want the angle Ø so that cosØ = √3/2 of course you should recognize that as a ratio form our 30-60-90 triangle, and Ø = 30° for tan^-1 (-√11/√5), construct a triangle in quadrant II ...

*May 2, 2016*

**Probability and statistics**

prob(choosing child) = 6/12 = 1/2 prob(non-child) = 1- 1/2 = 1/2 prob(exactly one child in choosing two) = C(2,1) (1/2)(1/2) = 1/2 or If C stands for choosing child and N stands for non-child we have these cases: CC -- prob = (1/2)(1/2) = 1/4 CN -- 1/4 NC --1/4 NN -- 1/4 so ...

*May 2, 2016*

**Math**

The least perimeter is obtained when you have a square let the side be s s^2 = 32 s = √32 = 4√2 so the least perimeter is 8√2 by Calculus: let the width be x then the length is 32/x P = 2x + 2y = 2x + 64/x P' = 2 - 64/x^2 = 0 for a min of P 2 = 64/x^2 x^2...

*May 2, 2016*

**Math**

Well, your homework is poorly stated. Here is an example of what Steve is saying: suppose the width is .1 ft then the length = 39/.1 or 390 ft perimeter = 2(390) + 2(.1) = 780.2 ft check: area = .1(390) = 39 suppose the width is .001 ft then the length is 39/.001 or 39000 ft ...

*May 2, 2016*

**Geometry**

3 small ones of 5 in diameter v = 3((4/3)π(2.5)^3) = 125π/2 = 62.5π = appr 196.35 one of diameter 8 v = (4/3)π(4^3) = 256π/3 = appr 268.08 hemisphere of radius 5 = (1/2)(4/3)π(5^3) = 250π/3 = appr 261.8

*May 2, 2016*

**Probability and statistics**

we can build our 5 digit number using 5 different numerals all possible numbers = 5! or 120 In all of these, the lead digit, the 10-thousand digit, can be occupied by the "9" 24 times, the "8" 24 times, etc. The value of those 24 9's would be 24(90000...

*May 2, 2016*

**Gr 11 Functions**

(1+tanx)^2 ≠ (1-sinx)(1+sinx) RS = 1 - sin^2 x = cos^2 x and cos^2 x is certainly not equal to (1+tanx)^2 try x = 45° (1+tan45)^2 = (1+1)^2 = 4 cos^2 (45°) = (1/√2)^2 = 1/4 no wonder you got nowhere with your work. check the question, or check your typing.

*May 2, 2016*

**Correcion - math**

Sarim's solution above makes absolutely no sense consider this one: http://www.jiskha.com/display.cgi?id=1462219074

*May 2, 2016*

**maths**

I know that the cost of coffee has gone up, but $2000 per kg ???? I will assume that you meant $22.00, (even that is too high) anyway..... let the cost of the mix be $x per kg 8(20) + 12(22) = x(8+12) 20x = 424 x = $21.20

*May 2, 2016*

**math**

looks for every increase of 1 unit in the x's the corresponding y decreases by 5 so slope = -5 y = -5x + b at x = -2, y = 9 9 = -5(-2) + b b = -1 function rule: y = -5x - 1

*May 2, 2016*

**Math**

I have no idea what your line 42pi C=pi*d=pi.pi*42=42pi. is supposed to say or mean. Are you saying the C = 42π ?? in that case the radius would be 21 units and the answer is in exact form now if we use the approximation of 22/7 for π we get C = 42(22/7) = 132 42&#...

*May 2, 2016*

**Algebra**

yes, the new vertex will be (4,-1) proof: f(x-2) = (x-2)^2 - 4(x-2) + 3 = x^2 - 4x + 4 - 4x + 8 + 3 = x^2 - 8x + 15 = g(x) vertex of g(x) = -b/(2a) = 8/2 = 4 g(4) = 4^2 - 8(4) + 15 = -1 vertex is (4,-1)

*May 2, 2016*

**calculus**

a) let the top right vertex be (x,y) then the area = 2xy A = 2xy = 2x(16-x^2) = 32x - 2x^3 dA/dx = 32 - 6x^2 = 0 for a max of A 6x^2 = 32 3x^2 = 16 x^2 = 16/3 x = 4/√3 , then y = 16 - 16/3 = 32/3 so the rectangle has a base of 2(4/√3) = 8/√3 and a height of ...

*May 2, 2016*

**calculus**

sum(1) = 1^3/1^4 = 1 or 4/4 sum(2) = (1 + 8)/16 = 9/16 sum(3) = (1+8+27)/81 = 36/81 = 4/9 or 16/36 sum(4) = (1+8+27+64)/256 = (1+8+27+64)/256 = 100/256 = 25/64 sum(5) = (1+8+27+64+125)/625 = 225/625 = 9/25 = 36/100 I noticed I can change my numerator to (n+1)^2 for sum(n) and ...

*May 2, 2016*

**calculus**

recall that tan^2 A +1 = sec^2 A and d(tanA)/dA = sec^2 A so ∫ tan² x/3 dx = ∫ sec^2 (x/3) - 1 dx form 0 to π = [3 tan (x/3) - x] from 0 to π = 3tan π/3 - π -(3tan 0 - 0) = 3 √3 - π

*May 2, 2016*

**maths**

volume of cube = (5.5 cm)^3 = 166.375 cm^3 then our cylinder's height would increase by h , such that π(49)h = 166.375 h = 1.081 cm (note that the 9 cm depth of water did not enter the picture)

*May 2, 2016*

**Calculus**

let the water level have a radius of r ft let the height of the water be h ft by ratio: r/h = 5/12 12r = 5h ---> r = 5h/12 V = (1/3)π r^2 h = (1/3)π(25h^2/144)(h) = (25/432)π h^3 dV/dt = (25/144)π h^2 dh/dt plug in our given stuff 1 = (25/144)π(64) ...

*May 2, 2016*

**Calculus**

dy/dt = 2ax dx/dt + dx/dt dy/dt = dx/dt(2ax + 1) but dy/dt = dx/dt , so 1 = 2ax + 1 2ax = 0 x = 0 then y = b at the point (0,b)

*May 2, 2016*

**Calculus**

did you make your sketch ?? let the length of the man's shadow be x ft let the distance he is from the lightpost be y by ratios: 6/x = 15(x+y) 6x + 6y = 15x 6y = 9x 2y = 3x 2dy/dt = 3dx/dt but dy/dt = 3 so 6 = 3 dx/dt dx/dt = 2 His shadow is lengthening at 2 ft/s but he is...

*May 2, 2016*

**Math**

your def: a*b= a+b-ab = first + last - product of first times last (a*b)*c = (a+b-ab)*c = a+b-ab + c - ac - bc + abc = a+b+c - ac - ab - bc + abc a*(b*c) = a*(b+c - bc) = a+b+c-bc - ab - ac + abc = a+b+c - ac - ab - bc + abc = (a*b)*c so the operation is associative -5*8 = -5+...

*May 2, 2016*

**calculus too hard help**

let's try this: let y = x^x lny = xlnx y'/y = x(1/x) + lnx dy/dx = y(1 + lnx) = x^x + x^x(lnx) let u = x^x^x , the x's are staggered ln u = x ln(x^x) u'/u = x(x^x + x^x(lnx))/x^x) + ln(x^x) argghhhh!! I was looking for a pattern. What am I not seeing ????

*May 2, 2016*