Tuesday
December 6, 2016

Posts by Reiny

Total # Posts: 36,897

Maths
x ÷ (3/4) = 3 x(4/3) = 3 x = 9/4 check: (9/4) ÷ (3/4) = (9/4)(4/3) = 36/12 = 3
September 15, 2016

maths need help
make a sketch you will need the incentre of the triangle. This consists of the intersection of the angle bisectors label the triangle ABC, with the incentre O. Sketch in the three radii, hitting sides AB, BC, and CA at P, Q, R respectively. You should see that we have 3 pairs ...
September 15, 2016

math
see my reply to your earlier post of this http://www.jiskha.com/display.cgi?id=1473901698
September 14, 2016

math
See http://www.jiskha.com/display.cgi?id=1473903464 when you were Madison PS. by sheer coincidence "helppp's" solution is identical to mine.
September 14, 2016

Algebra
y = (-1/4)x + 648
September 14, 2016

trigonometry
cot^-1 27 is the angle Ø so that cotØ = 27 or tanØ = 1/27 my calculator gives me appr 2.12°
September 14, 2016

trigonometry
clear case of right-triangle trig height/65 = tan 35° height = 65tan35° = ....
September 14, 2016

math
correct
September 14, 2016

math
Just translate the English to Math let the number be x "Eleven more than twice a number has the same value as 8 times 'the difference of the number and 5" 11 + 2x = 8(x-5) solve for x , let me know what you got Hint: it is not a whole number
September 14, 2016

math
width--- x length --- 2x + 5 solve for x and sub into my definitions: 2x + 2(2x+5) = 232
September 14, 2016

math
According to my solution the 3 numbers are 55, 56, and 57 sum of the first two = 55+56 = 111 117 less than 4 times the larger = 4(57) - 117 = 111 Well, what do you know, it works
September 14, 2016

math
smallest number ---- x middle number ------ x+1 larger number --------x+2 x + x+1 = 4(x+2) - 177 2x+1 = 4x+8-117 -2x = -110 x = 55 the smallest is 55
September 14, 2016

math
Isabella's age --- x John's age ----- 2x - 17 x + 2x-17 = 40 solve for x and sub into my definitions
September 14, 2016

Math
"place-value reasoning" ? In my days we called it division, that is amount in each bag = 5.5/50 = .11 kg or 110 grams
September 14, 2016

correction - typo - math
x + 2x+5 = 17 3x = 12 x = 4 So Jessica is 4 and Sam is 13
September 14, 2016

math
Good grief, bobpursely gave a perfectly good answer when you posted as 8thgradestudent as did Graham http://www.jiskha.com/display.cgi?id=1473900151 please don't switch names, it causes the same question being answered unnecessarily . Here is another shot at it: Jessica&#...
September 14, 2016

math
Hey, it is your question, you typed it. I expressed my confusion of your typing. If 32800 are the school expenses, then we don't know his salary, let it be x after school expenses he has x - 32800 after spending 1/4 of that in savings he will be left with (3/4)(x-32000) or...
September 14, 2016

math
Hard to understand your typing. I assume the monthly salary is 32,000 and he used .2 of that for school fees, so he used 6400 for school fees, leaving him with 25,600 he used 1/4 of that to deposit, or he deposited 6400, leaving him with 19,200 for other expenses.
September 14, 2016

Math
Let the job of cleaning the room be 1 unit Tom's rate = 1/45 Wally's rate = 1/30 combined rate = 1/45 + 1/30 = 1/18 room/min job left to be done after 5 minutes = 1 - 5(1/18) = 13/18 let Gigi's rate be 1/x so total combined rate = 1/18 + 1/x = (x+18)/(18x) so (13/...
September 14, 2016

for Asha - maths
total value of his property ---- 60,000,000 wife's share = (1/5)(60,000,000) = 12,000,000 son & daughters share = 30,000,000 son's share --- 2x daughter's share --- x 2x + x = 30,000,000 x = 10,000,000 So the son gets 20,000,000 and the daughter gets 10,000,000 ...
September 14, 2016

Math
So for Sinea it was snacks : games : souv = 5 : 8 : 12 or 5x : 8x : 12x then ... 5x+8x+12x = 40 25x = 40 x = 1.6 Then Sinea spent the following: snacks = 5x = 8 games = 8x = 12.50 souvenirs = 12x = 19.20 Now repeat the same steps for Ren sn : ga : sou = 10 : 8 : 20 = 5 : 4 : ...
September 14, 2016

Math
What was the ratio ?
September 14, 2016

Math
speed of wind --- x km/h speed against the wind = 350-x km/h speed with he wind = 350+x km/h 169/(350-x) = 190/(350+x) cross-multiply and solve for x
September 14, 2016

Math
the number --- x its reciprocal --- 1/x x - 30/x = 1 times x x^2 - 30 = x x^2 - x - 30 = 0 (x - 6)(x + 5) = 0 x = 6 or x = -5, but a natural number is positive, so x = 6 check: 6 - 30(1/6) = 6 - 5 = 1 looking good.
September 14, 2016

math2
ax+by+c=0 ----> bx-ay+c=0 What that says is : interchange the coefficients of the x and y terms then change the sign of the y term to its opposite. Remember, it is considered to be "good form" to have the x term at the front as a positive term. e.g. 5x + 7y + 9 = ...
September 14, 2016

Math
S50E vs S40W Doesn't that form a 90° angle? So you have a right-angled triangle with legs of 7 and 24, and you are looking for the hypotenuse. Pythagoras anyone ?
September 14, 2016

Math
It asked for zebras : total = 2 : 16 = 1 : 8 , not 8 : 1
September 14, 2016

Algebra
let the three consecutive odd integers be x, x+2, and x+4 3x + 2(x+2) = 4(x+4) - 11 solve for x and sub into my definitions
September 13, 2016

Math
let the rate of growth be r then 326(1+r)^6 = 10,000 (1+r)^6 = 30.6748.. ( I stored it in memory for accuracy) take 6th root of both sides 1+r = 30.6748^(1/6) = 1.76928... or , using GS a = 326 r = ? 2004 ---> term 1 = a 2010 ----> term 7 = ar^6 326 r^6 = 10000 r^6 = ...
September 13, 2016

Math pre algebra please help with ?
1/2x -5 +2/3x=7/6x+4 multiply each term by 6 , the LCD 3x - 30 + 4x = 7x + 24 I am sure you can handle this equation.
September 13, 2016

maths
unit digit is x tens digit is x-5 the actual number is 10(x-5) + x the number reversed is 10x + (x-5) 10x + (x-5) - (10(x-5) + x) = 7 10x + x - 5 - (10x - 50 + x) = 7 11x - 5 - 11x + 50 = 7 45 = 7 , which is a contradiction There is no solution The question is bogus. e.g. ...
September 13, 2016

Math
Is ABC a triangle? Is D on AC ?
September 13, 2016

math
8² +9(12÷3 x 2) -6 I get: 64 + 9(8) - 6 = 64 + 72 - 6 = 130 http://www.wolframalpha.com/input/?i=8%C2%B2+%2B9(12%C3%B73+x+2)+-6
September 13, 2016

Calculus
should have been -5 / ( 2√(73-5x) ) perhaps you just had a typo, check your work
September 13, 2016

oops - Math
I misread the question. Should have been North American = 30 , not European. I also noticed that I answered the same question back in 2014 without making that error, look at the first of the Related Questions below.
September 13, 2016

Math
since SA to E is 3:2 let SA be 3x and E be 2x given E = 30 so 2x = 30 x = 15 So we know there are 3x or 45 South American and 30 Europeans, (note 45:30 = 3:2) also NA : SA = 5:3 let NA be 5y and SA be 3y but we know 3y = 45 y = 15 so the number of North American butterflies = ...
September 13, 2016

algebra
speed of current --- x mph time to go 100 miles with the current = 100/(38+x) time to go 80 miles against the current = 80/(38-x) so 100/(38+x) = 80/(38-x) cross-multiply 3040 + 80x =3800 - 100x 180x =760 x = 760/180 = 38/9 mph the current is appr 4.2 mph
September 13, 2016

Math
??9 (x+1)x9 but x+1 + x = 11 2x = 10 x = 5 the number is 659 Where do the "blocks" enter the picture?
September 13, 2016

math
How about you try this one. Let me know what you did
September 13, 2016

math
JM's mass ---- x Dad's mass --- 7x/3 7x/3 = x + 36 7x = 3x + 108 4x = 108 x = 27 total = x + 7x/3 = 27 + 27(7/3) = 27 + 63 = 90 kg
September 13, 2016

math
reds ---- x greens --- 4x total ---- 5x ratio of greens to total = 4x : 5x = 4 : 5
September 13, 2016

Math
prob(success) in a single toss = 3/8 prob(3 successes in 6 tries) = C(6,3) (3/8)^3 (5/8)^3 = 20(27/512)(125/512) = 67500/262144 = 16875/65536 = appr .257
September 13, 2016

Math HELP please!
0.42, - 1/2, 11/20, - 0.51 change them to decimals each having 2 decimals 0.42, - 0.50, 0.55, - 0.51 Now can you tell?
September 13, 2016

algebra 2
Yes, decreasing is from largest to smallest So to make her happy, just turn them around.
September 13, 2016

algebra 2
I will assume the _/13 is √13 , which would be the largest, so √13, π, 1.3, -.7, -8/5 are indeed in the correct descending order. If that is how you had it, and you did not have a typo, ask your teacher to reconsider.
September 13, 2016

Algebra
speed of boat in still water ---- x km/h speed of current ------- y km/h 7(x-y) = 28 or x - y = 4 4(x+y) = 48 or x + y = 12 add them: 2x = 16 x = 8 in x+y=12, if x = 8 , y = 4 state the conclusion
September 13, 2016

math
"p varies directly as q and the square of r and inversely as s " -----> p = k(qr^2/s) , where k is a constant find k if p=40 q=5 r=4 s=6 you are given the values of the 4 variables, sub them into the above equation to solve for k then rewrite the equation. let me ...
September 13, 2016

Maths Percentage
I will do the first one, you do the other two in the same way. "Emraan income is 25% more than that of Syed" ---> E = 1.25*S or (5/4)S S = E/1.25 or (4/5)E = .8E .8 = 1 - .2 or 100% - 20% Syed's income is 20% less than that of Emraan
September 13, 2016

geometery
angle A ---- x angle B ---- 55x angle C ---- 44x - 1111 x + 55x + 44x - 1111 = 180 100x = 1291 x = 12.91 55x = 710.05 Not possible as an angle in a triangle. This question makes no sense.
September 12, 2016

geometery
length ---- x width ---- (1/2)x - 3 2( x + x/2 - 3) = 42 x + x/2 - 3 = 21 (3/2)x = 24 x = 24(2/3) = 16 the length is 16 the with = (1/2)(16) - 3 = 5 check: 2(5) + 2(16) = 42 my answer is correct
September 12, 2016

algebra (check work)
What you want to express is that the height is between 4 and 18. Usually the same inequality sign is used with the smaller on the left and the larger on the right, thus 4 ≤ height ≤ 18 , or 4 ≤ x ≤ 18 if you want to use x
September 12, 2016

Math
2 x 3^x = 162 3^x = 81 <---- a power of 3 we know 3^4 = 81 so x = 4
September 12, 2016

precalculus
sketch a right-angled triangle. label the horizontal base as x the vertical side as y the hypotenuse as r, and the base angle as Ø memorize these ratios: sinØ = y/r cosØ = x/r tanØ = y/x and now their reciprocals: cscØ = 1/sinØ = r/y ...
September 12, 2016

precalculus
ok, I am supposing Ø to be as you stated, now what? did you notice that 35^2 + (-12)^2 = 37^2 ? Do you know the basic trig ratios in terms of the x, y, and r of the corresponding right-angled triangle?
September 12, 2016

Math
You are just guessing. As Steve suggested, show your steps so we can see how you obtained either -16 or 8 as your answers
September 12, 2016

Math
I would do it this way: 1.0(.1) + .89(.2) + (.82)(.55) + .81(.15) = .8505 or 85%
September 12, 2016

math
use your definitions. a = 7.5 a+ 3d = 3 7.5 + 3d = 3 d = -1.5 sum(n) = (n/2)(2a + (n-1)d) -9 = (n/2)(15 + (n-1)(-1.5) ) -18 = n(15 - 1.5n + 1.5) -18 = 16.5n - 1.5n^2 double and re-arrange 3n^2 - 33n - 36 = 0 n^2 - 11n - 12 = 0 (n+1)(n-12) = 0 n = -1 or n = 12 there are 12 terms
September 12, 2016

math
younger tree --- x middle tree -----y older tree -------z x+y+z = 1000 * time for younger tree to reach age of current middle tree = y - x at that point: younger tree --- y middle tree --- y + y-x = 2y - x older tree ---- z + y-x 2y-x = z 2y-x = 4x 2y = 5x y = 5x/2 x + y + z...
September 12, 2016

math
just use your definitions e.g. term(3) = a + 2d , etc a+2d + a+6d = 38 2a + 8d = 38 a + 4d = 19 *** a + 8d = 37 ** subtract them: 4 d = 18 d = 9/2 or 4.5 into ** a + 72/2 = 37 a + 36 = 37 a = 1 the sequence is: 1 , 5.5, 10, 14.5, 19, 23.5, 28, ...
September 12, 2016

algebra homework help
−( 3x + 3 ) + 2( 2y + 2 ) = -3x - 3 + 4y + 4 = -3x + 4y + 1
September 12, 2016

algebra help needed
no it isn't 5(x+y)-(x+y) = 5x + 5y - x - y = 4x - 4y but 15(x+y)-(x+y) = 15x + 15y - x - y = 14x - 14y so you clearly had a typo in your original post
September 12, 2016

algebra help needed
no, how can 5x - x = 6x ? if you have 5 apples and take one away ..... 5(x+y)-(x+y) = 5x + 5y - x - y = ...
September 12, 2016

math
width --- x length --- x+6 x(x+6) = 42 x^2 + 6x - 42 = 0 x^2 + 9x + 9 = 42+9 (x+3)^2 = 51 x+3 = √51 x = √51 - 3 = appr 4.14 width is 4.14 , length is 10.14 check: 4.14(10.14) = appr 41.9796 , close enough for my round-off I assume you know how to solve a quadratic ...
September 12, 2016

Algebra
Oh my!!! you are dealing with a multiplication and division of numbers, why are you adding them ? your question: (5.6x10^5) (9.9x10^-8) /( (8.4x10^-4) (5x10^6) ) = (5.6)(9.9)(10^-3) / ((8.4)(5)(10^2) ) = 55.44x10^-3 /(42 x 10^2) = 1.32 x 10^-5 look at my solution line by line...
September 12, 2016

Algebra
.8x = 20.8 x = 20.8/.8 = ....
September 12, 2016

Algebra
follow the method I just showed you. let me know what you get.
September 12, 2016

Algebra
in scientific notation , we use a single digit followed by a decimal x a power of 10 so you want the decimal to be after the 6 6.2 x 10^8 that is, assume that the decimal is at the end of 630,000,000. Now count how many places I moved it to get to be after the 6
September 12, 2016

Algebra
key point: at the "overtaking" they both will have gone the same distance in a time 2 hrs apart. let the time taken by the jet be t hrs then the time taken by the small plane be t+2 hrs 900t = 180(t+2) 900t = 180t + 360 720t = 360 t = 1/2 then 900t = 450 they will be...
September 12, 2016

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

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