Friday
December 9, 2016

Posts by Reiny

Total # Posts: 36,929

profit and loss
original cost per egg --- x cost per egg after reduction = .8x number of eggs for rs 10 at x = 10/x number of eggs for rs 10 at .8x = 10/(.8x) = 12.5/x 12.5/x - 10/x = 6 2.5x = 6 x = 6/2.5 = 2.4 original cost per dozen = 12(2.4) = Rs 28.8 check my arithmetic
September 12, 2016

College Math
what is (8/9)(4/3) ?
September 12, 2016

math
Now: Pam's age --- x Lara's age --- x+5 5 years from now: Pam is x+5 Lara is x+5 + 5 = x+10 x+5 + x+10 = 32 carry on
September 12, 2016

Math
ask yourself .. 12 times what is 24 ---> 2 12 times what is 36 --->3 so 24+36 = 12(2 + 3)
September 10, 2016

s.g (math)
btw, as an aside to your question ... Any angle subtended by a diameter is a right-angle, so you would have the 5-12-13 right-angled triangle. the larger of the acute angles is arctan(12/5) and the smaller is arctan(5/12) ---> appr 22.6° note: sin^2 22.6° + cos^2 22...
September 10, 2016

s.g (math)
Is this supposed to be a trick question? sin^2 Ø + cos^2 Ø - 1 = 1 - 1 = 0 the fact that we have a triangle of sides 12 and 5 in a circle has nothing to do with it.
September 10, 2016

Algebra
(2 x^-2 y^6)^4 / (4x^3 y^-4)^2 = (16x^-8 y^24)/(16 x^6 y^-8) = x^-14 y^32
September 9, 2016

math
look at Ms Sue's solution for this question http://www.jiskha.com/display.cgi?id=1473473272 and then adjust it to yours.
September 9, 2016

Math
92/92 = 1 92/23 = 4 She can make 23 packets each containing 4 crayons and 1 sheet of paper.
September 9, 2016

Algebra
so you have (x^-2)^3 (x^2)^4 / x^15 then = (x^-6)(x^8)/x^15 = (x^2)(x^-15) = x^(-13) or 1/x^13
September 9, 2016

Math
check this http://www.jiskha.com/display.cgi?id=1176501726
September 9, 2016

Math
and .... ? what happened next?
September 9, 2016

Math
A's rate ---- 1/36 B's rate ----- 1/x combined rate = 1/36 + 1/x = (x+36)/(36x) 1/( (x+36)/(36x) ) = 20 36x/(x+36) = 20 36x = 20x + 720 16x = 720 x = 45 it would take 45 min for B alone
September 9, 2016

Math
V = -900t + 26500
September 9, 2016

Math
find rate of change: (3500 - 3185)/(1920 - 1927) rate of change = 315/-7 = -45 so P = -45t + b when t = 0, P = 3500 3500 = 0 + b b = 3500 P = -45t + 3500
September 9, 2016

Math
3t=(1)/(7+u) 21t + 3tu = 1 3tu = 1 -21t u = (1-21t)/(3t) , t ≠ 0
September 9, 2016

Math
I thing the 27.60 is the total, that is, it includes the tip. so , cost of each dinner --- x 3p(1.14) = 27.60 p = 27.60/(3(1.14)) I get p = $8.07 check: 3 dinners cost 3(8.07) = 24.21 tip = .14(24.21) = 3.39 total cost = 24.21 + 3.39 = 27.60 Patte's cost of p = 7.82 check...
September 9, 2016

math
The wording looks jumbled The exterior angle of an n-gon is 360/n and the exterior angle of an (n+1)-gon is 360/(n+1) so 360/n - 360(n+1) = 12 times n(n+1) , the LCD 360(n+1) - 360n = 12n(n+1) 360n + 360 - 360n = 12n^2 + 12n 12n^2 + 12n - 360 = 0 n^2 + n - 30 = 0 (n+6)(n-5) = ...
September 9, 2016

Science
using Calculus: v = at + c s = (1/2)at^2 + ct + k when t = 4 s = 8a + 4c + k when t = 5 s = (25/2)a + 5c + k (25/2)a + 5c + k - (8a + 4c + k) = 65 4.5a + c = 65 ** when t = 9 s = (81/2)a + 9c + k when t = 8 s = 32a + 8c + k (81/2)a + 9c + k - (32a + 8c + k) = 105 8.5a + c = ...
September 9, 2016

Math
prob that the first 4 drawn contain NO black = (12/18)(11/17)(10/16)(9/15) = 11/68 so prob of at least 1 black = 1 - 11/68 = 57/68
September 9, 2016

Math
your question makes no sense. Did you mean "What is the probability of getting a white when drawing one marble" ? If so, that would be 5/27 or appr .185 or appr 18.5%
September 9, 2016

MATH
since a + b = π/2 a and b are complimentary angles thus sin b = cos a we know sin a = 1/3 make a sketch of your right-angled triangle, find the adjacent side to be √8 thus cos a = √8/3 so sin b = √8/3 or 2√2/3
September 9, 2016

math
If you just go for a single topping for each flavour, then it is simply 8x10 or 80 different desserts. On the other hand, if you can have no topping, one topping, two toppings, etc for each of the flavours, it becomes an entirely different question. Did you mean the latter case ?
September 9, 2016

math
width ---- x length ---- 4x - 7 solve for x, then sub into my definition 2x + 2(4x-7) = 46
September 9, 2016

math
17-4x=67-9x add 9x to both sides 17 - 4x + 9x = 67 - 9x + 9x simplify 17 + 5x = 67 subtract 17 from both sides 17-17 + 5x = 67-17 simplify 5x = 50 divide both sides by 5 5x/5 = 50/5 simplify x = 10 done!
September 9, 2016

Math
just add them: 2x = 12 x = 6 Now subtract them 2y = 2 y = 1 done
September 9, 2016

math 101
It would take 24 janitor-hours to do the job so for 6 janitors it would take 24 janitor-hours/6janitors = 4 hours, (the janitors would cancel)
September 9, 2016

Math
In a function, the same x value cannot have 2 or more different y values This happens in C and D, so those two are NOT functions That leaves A and B, but A led me to the objection I first stated.
September 9, 2016

Math
poor wording, you must have meant three "different" values.
September 9, 2016

Math
Make a sketch of a circle, draw in the diameter The largest square would have a diameter of 8 mm, which would be the hypotenuse of the right-angled triangle created by that square. Let the side of the square be x x^2 + x^2 = 8^2 2x^2 = 64 x^2 = 32 area of square = (x)(x) = x^2...
September 9, 2016

Math
volume of the 2 spheres = (4/3)π (1^3 + 2^3) = (4/3)π(9) = 12π cm^3 volume of cylinder = π r^2 h 12π = π(r^2)(1) r^2 = 12 r = √12 or 2√3 cm = appr 3.464 cm
September 9, 2016

Math
Palindromic numbers , depends on what you want, single digit numbers: 1 2 3 4 5 double digit numbers: 11 22 33 44 55 triple digit numbers: 111 121 131 141 151 Triangular numbers: look at the number of billiard balls that can be placed in the standard triangle used in billiards...
September 9, 2016

pre calc
You must memorize the pattern of the standard circle and the information it provides centre is (1, -8) radius = √16 = 4
September 9, 2016

Math
The largest bin (largest area) is obtained when you have a square, so each side is 25/4 ft and the largest area is (25/4) ft^2 = 625/16 ft^2 or 39.0625 ft^2
September 8, 2016

Math
#1, from the 2nd, e = 4 sub that into the first: 7w + 4 = 8 7w = 4 w = 4/7 I feel suspicious that this problem contained a typo #2 just use substitution, since 7e = 107 - 6d in the 2nd: 107 - 6d + 8d = 117 2d = 10 d = 5 then 7e = 107 - 6(5) 7e = 77 e = 11
September 8, 2016

Algebra
2(2x+3) + 2(x-6) = 90 4x + 6 + 2x - 12 = 90 6x = 96 x = 16
September 8, 2016

math101
.5/20 = 9/x .5x = 180 x = 360 km apart or 1/2 cm represents 20 km 1 cm represents 40 km so 9 cm represents 9(40) or 360 km
September 8, 2016

maths
length --- 9x width ---- 7x 2(9x) + 2(7x) = 144 solve for x, sub back into my definitions
September 8, 2016

Marh
They would have traveled the same distance, let that distance be x km time for jet = x/900 time for plane = x/180 x/180 - x/900 = 2 solve for x hint: multiply each term by 900 , the LCD
September 8, 2016

Math
You are Liana
September 8, 2016

Math
looks like the same problem I just solved for you except you changed one number. Repeat my steps
September 8, 2016

Math
rate of plane --- x km/h rate of car ------ x-120 km/h time for plane = 1260/x time for car = 429/(x-120) 1260/x = 429/(x-120) cross- multiply .... 1260(x-120) = 429x carry on
September 8, 2016

Math
last mark needed ---- x (94+98+98+x)/4 = 96
September 8, 2016

Intermediate Algebra
width --- x length ---- x+9 x(x+9) = 286 x^2 + 9x - 286 = 0 (x - 13)(x + 22) = 0 x = 13 or x is a negative the garden is 13 by 22
September 8, 2016

liberal arts math
1-.1 = .9
September 8, 2016

Math
44/3 is not equal to 14.6, it is 14.6666.... so you have used a truncated decimal, so your answer is not exactly the same. The problem is that 44 does not divide by 3 exactly. try this on your calculator: 31.5 x 14.66666... (enter as many 6's as you can) you should get 461...
September 8, 2016

Math
no! when adding fractions with the same denominator like we have here, you add the numerators only and keep the denominator. 21/2 plus 21/2 plus 21/2 = 63/2 and (63/2)(44/3) = 2772/6 = 462 In my actual calculation, I would have cancelled the 3 into the 63 --> 21 and the 2 ...
September 8, 2016

Math
That would work, since the width is apparently the same for all three, so is the length. total area = (21/2)(44/3) + (21/2)(44/3) + (21/3)(44/3) = 462 or = (44/3)(21/2 + 21/2 + 21/2) <---- your way = 462 or, even simpler = 3(21/2)(44/3) = 462
September 8, 2016

Math
looks like just 3x3x3 or 27 to me
September 8, 2016

Math
it said "to use 2/5 of the paint" the English word "of" usually indicates that you would be multiplying. eg. give me 1/2 of $6.00 so (1/2)(6.00) = $3.00 Very often, creating a simpler problem with easy numbers let's you get the answer by simple common ...
September 8, 2016

Math
correct
September 8, 2016

Math
did you mean that the larger root is x = 5 ? (x-5) would be one of the factors. then if f(x) = x^2 - 5x+ k f(5) = 25 - 25 + k = k for x=5, f(5) must be zero, so k = 0 check: you would have: x^2 - 5x = 0 x(x-5) = 0 roots are 0 and 5, and sure enough 5 is the larger.
September 8, 2016

Math
Wow, first of all , I think you meant: (√6+√11) * (√3+√3+√11) * (√3+√6+√3+√11) * (√3-√6+√3+√11) Did you really mean for that to be multiplied? Very tedious and long which I don't feel like doing...
September 8, 2016

@ Andarah - maths
It was sheer coincidence that you ended up with the correct answer. Where did you get (5-3) from ?? correct solution steps: 3x-5 = 10 3x = 10+5 3x = 15 x = 15/3 x = 5
September 8, 2016

maths
3x-5 = 10 solve for x
September 8, 2016

math
actual number of oranges ---- x number of fresh oranges = x-15 number of apples = x+40 x + x+40 = 568 2x = 528 x = 264 number of oranges = 264 number of apples = 304 number of fresh oranges = 264-15 = 249 apples - fresh oranges = 304-249 = 55
September 8, 2016

Algebra 2
just plug in 3 wherever you see an x p(3) = 2(3^3) + 8(3^2) - 7(3) = 54 + 72 - 21 = ...
September 8, 2016

math
Did you make a sketch? on mine, I labeled the original point A, and the closer point B. Top of the church P, bottom of church Q AB = 30, angle A = 35°, angle PBQ = 55° in triangle PAB, angle PBA = 125°, then angle APB = 20° by the sine law: BP/sin35 = 30/sin20 ...
September 8, 2016

Algebra II
Here is a cute little video from the KhanAcademy to show the basic method. It will depend on how you were taught whether you divide by 7 or by 6. You will have to check your notes or your textbook https://www.khanacademy.org/math/statistics-probability/displaying-describing-...
September 7, 2016

Math
notice that the difference in your inputs in 1, while the difference in your outputs is 3 so you have a slope of 3 let's start with y = 3x + b when x = 2, y = 2 so 2 = 3(2) + b -4 = b f(x) = 3x - 4 check with a few values.
September 7, 2016

Algebra
#4, oh dear!!! (2x-3)(4x+3) = 8x^2 + 6x - 12x - 9 = 8x^2 - 6x - 9 #5 , same as #4 (4x-3)(4x+3) = 16x^2 + 12x - 12x - 9 = 16x^2 - 9 <--- called the difference of squares make sure you are familiar with FOIL, F : multiply the firsts O : multiply the "outers" I : ...
September 7, 2016

Algebra
#2: (4h^3+3h+1)-(-5h^3+6h-2) think of it as (4h^3+3h+1)-1(-5h^3+6h-2) = 4h^3 + 3h + 1 + 5h^2 - 6h + 2 = 9h^2 -3h + 3 #3 5k (3-4k) = 15k - 20k^2 by the distributive property
September 7, 2016

math
c + 2s = 10 3c + 2s = 18 subtract them: 2c = 8 c = 4 then 4+2s=10 s = 3 poor way to type it, at first I though the chalk and 2 staples cost $10.30
September 7, 2016

No --- Algebra 1
number of boys --- 7x number of girls --- 2x 2x = 48 x = 24 number of boys = 7x = 7(24) = 168 there are 168 boys. your ratio equation should have been 7/2 = x/48 2x = 336 x = 168
September 7, 2016

Algebra
Assuming your figure is a rectangle ... perimeter = sum of all 4 sides = 15/6 + 15/6 + 15/6 + 15/6 = 60/6 = 10 Why you would do: 15+ 15+15+15 and divided by 4 is beyond me.
September 7, 2016

Algebra
g(6) = 6^2 - 5 = 31 f(g(6)) = f(31) = -2(31) - 1 = -63
September 7, 2016

mathematics
after giveaway: greg has (2/3)x after sale he has (2/3)(2/3)x = (4/9)x (4/9)x=80 x = 180 take over
September 7, 2016

Math
(x,y) ---> (x-5, y + 11)
September 7, 2016

Math
390 was the total, so number of adults --- 8x number of kids ----- 5x 8x+5x = 390 13x = 390 x = 30 so 240 adults and 150 kids check: 240+150 = 390 240 : 150 = 24:15 = 8 : 5
September 7, 2016

9th grade algebra
#1, done well #2, your sketch should look like this http://www.wolframalpha.com/input/?i=plot+f(x)+%3D+-5%2F6x+,+g(x)+%3D+2%2F5x+%2B+4 look at the 2nd graph looks like appr (-3.25, 2.5) to me, so your guess is close your check: f(x): 2.5 =-5/6(-3.1) 2.5 = -2.58 <----- ...
September 7, 2016

Math - vectors
so you want: (14, - 12) = k(4, t) that is, 14 = 4k and -12 = kt 4k = 14 k = 14/4 = 7/2 then kt = -12 (7/2)t = -12 t = -12(2/7) = -24/7
September 7, 2016

Two bus trvl in opposite direction frm that same rtarting point.if d speed of 1 is twice d speed of d other and de 240km
Repost your question using the English language.
September 7, 2016

Math
speed of boat in still water ---- x mph speed of current ---- y mph (1/2)(x+y) = 10 x + y = 20 2(x-y) = 10 x - y = 5 add them 2x = 25 x = 12.5 then y = 7.5 state the conclusion.
September 7, 2016

Alg 1
so far you have a total of 251 lowest mark needed: (251+x)/4 >84 251+x > 336 x > 85 highest mark needed: (251+x)/4 < 86 251+x < 344 x < 93 possible scores are 86, 87, 88, 89, 90, 91, and 92 Question: why would you NOT want a score highter than 86 ?
September 7, 2016

math
-2 ( 4x - 3y + 18) = -8x + 6y - 36 , using the distributive property
September 7, 2016

math
1+2y<23 2y < 22 y < 11
September 7, 2016

Geometry
To me a two column proof is usually associated with Euclidean Geometry. To use it here in this rather simplistic problem is like using a sledge hammer to drive in a finishing nail ... here is what I would do 7y=8x-14; y=6 then: 42 = 8x - 14 56 = 8x x = 56/8 = 7 There! I have ...
September 7, 2016

math
5(x + 10) + x 6x + 15 5x + 15 6x + 50 4x – 50 ?? took me a while to realize that you just linked the possible answers together, which of course makes no sense if the question is simplify 5(x + 10) + x I don't understand why you are having problems clearly saying &...
September 7, 2016

Math
I am looking but can't see the shelf
September 6, 2016

Algebra
let the number of weeks be w when is 900 - 10w = 500 + 15w solve for w
September 6, 2016

Math
10×10^4+2.8×10^6 = 100,000 + 2,800,000 = 2,900,000 or 2.9 x 10^6
September 6, 2016

Math
1. check with your textbook, the rules should be there 2. check with your classroom notes, you must have them written down 3. Google your terms like "properties of negative exponents"
September 6, 2016

math
Wouldn't the new band have a radius a little larger than the original? I suspect a typo, and will assume it to be larger C = 2πr 40000 = 2πr r = 6366.197723676.. km new circumference = 40000.002 new r = 6366.23676 km difference = 0.00031831 km = .31831 metres or ...
September 6, 2016

math
let the piece formed into the first square be x cm then the piece formed into the second square is 5-x cm area of first square = (x/4)^2 = x^2/16 area of 2nd square = (5-x)^2/16 4x^2/16 = (5-x)^2/16 4x^2 = 25 - 10x + x^2 3x^2 + 10x - 25 = 0 (3x-5)(x+5) = 0 x = 5/3 or x = -5, ...
September 6, 2016

Math
Don't tell me they don't teach long division any more ! 54/6.75 = 5400/675 now divide
September 6, 2016

Algebra
I am going to call the middle number x, then the smaller is x-2, and the larger is x+2 Now just translate the English to Math: the sum of ----> + 5 times the smaller ---> 5(x-2) number a twice the larger ---> 2(x+2) the sum of 5 times the smaller number a twice the ...
September 6, 2016

Fractions
area of triangle = (1/2)base x height = (1/2)(7/8)(6/5) = 21/40
September 6, 2016

Math
follow the steps I used here for a similar question. http://www.jiskha.com/display.cgi?id=1473175123
September 6, 2016

Math
remember when multiplying powers of the same base we add the exponents 5m^4/3(m^1/3*2n^1/8) = 10 m^(4/3) n^(1/8)
September 6, 2016

Math
number of ones --- x number of twenties --- x-15 number of fives = 37 - x - (x-15) = 52 - 2x x + 5(52-2x) + 20(x-15) = 191 solve for x, then sub back into my definitions.
September 6, 2016

Linear Algebra
have you learned that any linear vector can be expressed as (rcosØ , rsinØ) where r is the magnitude and Ø is the angle it makes with the horizontal. so vector u = (15cos30°, 15sin30°) = (15√3/2 , 15/2) and vector v = (17cos55, 17sin55) u*v...
September 6, 2016

algebra 1
your choices were all correct
September 6, 2016

MATH
You can round off your daily cost when stating it, but you should carry more accuracy when you then multiply it by 7 or 30 e.g. #1 cost per pill = 1740/300 cents or 6 cents cost for 2 pills = 2(5.8) = 11.6 or 12 cents cost per week = 7(11.6) = 81.2 or 82 cents cost per month...
September 6, 2016

algebra 1
cost = 25 + 14m so if m = 6 cost = 24 + 14(6) = ...
September 6, 2016

algebra 1
correct
September 6, 2016

math
areas are proportional to the square of their diameters area of larger circle : area of smaller circle = 4^2 : 6^2 = 16 : 36 = 4 : 9
September 6, 2016

Algebra
3x^2-3y=12x+9 divide by 3 and re-arrange y = x^2 - 4x - 3 complete the square ... y = x^2 - 4x + 4 - 4 - 3 = (x - 2)^2 - 7 http://www.wolframalpha.com/input/?i=plot+y+%3D+(x+-+2)%5E2+-+7 axis of symmetry: x = 2
September 6, 2016

Math
amount in the pail --- x ml amount in the tank ---- 8346 - x ml (8346-x) + 314 = 12(x-314) 8660 - x = 12x - 3768 12428 = 13x x = 956 state conclusion with proper units.
September 6, 2016

math
number of eggs bought --- x number of eggs sold ----- x-20 4(x-20)/(3x) = 1.2 = 6/5 20x - 400 = 18x 2x = 400 x = 200
September 6, 2016

math
Since the volume is lwh, and we know h = x+1 then the base is lw = (x^3 + 3x^2 + 2x - 5)/(x+1) = (x^2 + 2x) - 5/(x+1) I had expected the division to be exact. Is there a typo?
September 6, 2016

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