Wednesday
February 10, 2016

Posts by Reiny

Total # Posts: 32,885

Geometry
Huh?
December 3, 2015

Math
you should have an angle after the word sin e.g. sinØ = -1/2 (without the angle it becomes a mathematical sin ) the reference angle is π/6, (because sin π/6 = +1/2 ) but your angle is in either quadrants III or IV in III: Ø = π + π/6 = 7π...
December 3, 2015

math
Assuming the data for Larry is linear, slope = (14.4 - 9.9)/(8-5.5) = 1.8 Larry's equation would be y = 1.8x So Henry can do 1.6 laps per minute and Larry can do 1.8 laps per minute so who do you think can swim faster?
December 3, 2015

Geomertry
yes, in an equilateral triangle
December 3, 2015

Plane trigonometry
circumference of pulley = 36π cm 5 m = 500 cm so we need 500/36π revolutions/sec or appr. 4.42 revs/sec
December 3, 2015

math
I just love this applet for this work, replaces all those nasty charts and tables in the back of text-books http://davidmlane.com/hyperstat/z_table.html click on "value from an area" enter mean as 69 SD as 10 click on "between" to get $59 and $79
December 3, 2015

Math
width --- x length ---y area = xy new width = x+1/8 = (8x+1)/8 length = y new area = y(8x+1)/8 y(8x+1)/8 - xy = 5/8 times 8 y(8x+1) - 8xy = 5 8xy + y - 8xy = 5 y = 5 second case: width = x+1 length = y area = (x+1)(y) = xy + y increase in area = xy+y - xy = y = 5
December 3, 2015

algebra
just keep working at it ... f(1) = .2 f(2) = 2f(1)/5 + 1 = 2(.2)/5 + 1 = 1.08 f(3) = 2f(2)/5 + 1 = 2(1.08)/5 + 1 = 1.432
December 3, 2015

Calculus
I will assume you meant: s = 600/(1 + 49(.6)^t) = 600(1 + 49(.6)^t)^-1 then growth rate = s' = -600(1+49(.6)^t)^-2 (49ln.6)(.6)^t now you want the max of growth rate, so you need s'' and set that equal to zero and solve I suggest taking the product rule, and ...
December 3, 2015

Mathhh. Please help :(
looks like the x decreased by 5 and the y increased by 8, so (x,y) ----> ( x-5, y + 8)
December 3, 2015

Pre calculus
If B stands for any real number, then you are correct
December 3, 2015

maths: Lowest common multiple
you even titled your post as "Lowest common multiple", so clearly that suggests the way to do it 12 = 2x2x3 8 = 2x2x2 so we need 2x2x2x3 or 24 if every factor is to be included. no you need 24/12 or 2 packs of wieners, and you need 24/8 or 3 packs of buns notice 2x12...
December 3, 2015

Math
speed of slower train --- x mph speed of faster train --- x + 78 mph time of slower train to overtaking = 5 hrs (form 1:00 to 6:00) time of faster train to overtaking = 2 hrs 5x = 2(x+78) solve for x
December 2, 2015

English- Borders by Thomas King- One question
Thomas King is a First Nation author living in Canada. He is currently a professor of English at the University of Guelph (20 minutes from me). His most noted books are "Back of the Turtle (2014)" and " The Inconvenient Indian" (2012). Great books, I read ...
December 2, 2015

geometry problems
one angle ---- x other angle --- 90-x x = (1/5)(90-x) times 5 5x = 90-x 6x = 90 carry on...
December 2, 2015

MATH
let the tens digit be x let the unit digit by y x+y=6 ---> y = 6-x original number = 10x + y number reversed = 10y + x 10y + x = 3x 10y = 2x x = 5y then y = 6 - 5y 6y=6 y=1 and x=5(1) = 5 the original number is 51
December 2, 2015

Math
After a time of t seconds, the lengths of the two decreasing sides are 6+.1t cm each and the side which is increasing is 6 + .1t It will cease being a triangle if the sum of two sides equals the third side 6 + .1t = 2(6 - .1t) 6 + .1t = 12 - .2t .3t = 6 t = 6/.3 = 20 it will ...
December 2, 2015

7th Scholastic Math
It asked " By about what factor does the number of haunted houses hosted by charity groups exceed the number within amusement parks". I read that as, "by what number would you have to multiply the amusement park number by to obtain the charity number ? " so...
December 2, 2015

7th Scholastic Math
number run by charity = .66(4500) = 2970 number run by amusement = 315 leaving 1215 by independent bus. (check: .27(4500) = 1215 ) 2970 = k(315) k = 2970/315 = appr 9.4 we could have just taken: 66/7 which is the same result (notice 2970/315 reduces to 66/7 )
December 2, 2015

algebra
reflection over the x-axis: (x,y) ----> (x, -y) so A(10,2) ---> A'(10,-2) B(9,5) ---> take over
December 1, 2015

Math
20 miles/60 hours = 16 miles/ h hours 20h mile-hours = 960 mile-hours divide both sides by mile-hours 20h = 960 divide both sides by 20 h = 48
December 1, 2015

Algebra 1 check answers
clearly 1 = 3 is a false statement, so there is no solution (if your two equations are linear, you are looking at two parallel and distinct lines. They will never intersect, or "they will intersect when 1 = 3" , and when will that be ??
December 1, 2015

Algebra 2
so you want: (1/2)a = ae^(-.1483t) .5 = e^(-.1486t) take ln of both sides and use rules of logs -.1486t = ln .5 t = ln .5/-.1486 = appr 4.66 hours
December 1, 2015

maths
let the two numbers be x and y , where x is the larger geometric mean = √(xy) arithmetic mean = (x+y)/2 (x+y)/2- √xy = 2 √xy = (x+y)/2 - 2 square both sides xy = (x^2 + 2xy + y^2)/4 - 2(x+y) + 4 times 4 4xy = x^2 + 2xy + y^2 - 8x - 8y + 16 x^2 + y^2 - 2xy - ...
December 1, 2015

Himamaylan, math
done, look back to your previous post of this
December 1, 2015

batac national high school
son's age ---- x mother ------ 3x eight yrs ago: son ---- x-8 mom --- 3x-8 3x-8 = 5(x-8) + 4 3x-8 = 5x-40+4 -2x = -28 x = 14 mother now is 3x = 42 check: now: son--- 14 mom ---42 8 yrs ago: son =6 mom = 34 is 34 four more than 5x6 ?? YES
December 1, 2015

Algebra
let the width of the pathway be x ft width of garden = 60-2x , x < 30 length of garden = 100-2x , area of garden = (60-2x)(100-2x) = 6000 - 320x + 4x^2 area of plot = 6000 half of plot = 3000 4x^2 - 320x + 6000 = 3000 x^2 - 80x + 750 = 0 I will complete the square: x^2 - ...
December 1, 2015

Himamaylan, math
1/3:N=1/2:40/N 1/(3N) = N/80 3n^2 = 80 n^2 = 80/3 N = √(80/3) = appr 5.164
December 1, 2015

math
tanA = y/r = (√2 - 1)/1 y = √2 - 1 x = 1 so by constructing a triangle, we can find r r^2 = 1^2 + (√2 - 1)^2 = 1 + 2 - 2√2 + 1 = 4 - 2√2 secA(sinA)(ta^2 A) - cscA = (1/cosA)(sinA)(sin^2 A)/cos^2 A) - 1/sinA = sin^3 A/cos^3 A - 1/sinA = (sin^4 A - ...
December 1, 2015

Maths
total of the 4 numbers is 24 new numbers added, x and 2x new sum = 24 + 3x (24+3x)/6 = 5 24 + 3x = 30 3x = 6 x = 2 the numbers added were 2 and 4
November 30, 2015

Geometry
The orthocentre is the intersection of the altitudes of a triangle. You will need the equation of two of these and find their intersection Make a sketch: notice that LN lies on the x-axis, so the altitude from M is simply x = 10 that was too easy. let's find the altitude ...
November 30, 2015

Math
Rose, It was pointed out to you both by me and by Bosnian, that your question makes no sense. http://www.jiskha.com/display.cgi?id=1448886577 Yet you have posted it again the same way. Did you read our reply?
November 30, 2015

PreCalculas
check your typing your equation contains no l besides that, what is 1o ?
November 30, 2015

Math
clearly x^2 h = 20 ---> h = 20/x^2 OR x = √(20/h) so you have : cost = base + 4 sides = 20x^2 + 8(4xh) to get the other two, replace h with 20/x^2 to get it in terms of x or replace the x with √(20/h) to get it in terms of h
November 30, 2015

Math
Rose, it was pointed out to you by Bosnian that your question makes no sense, yet you keep asking questions pertaining to it. your equation is c(t) = 3t/t^2 + 1 which reduces to c(t) = 3/t + 1 Even at the beginning, when t=0, this would be undefined. That is, the concentration...
November 30, 2015

algebra
let the third number be x Now, just translate .... " the second number is 4 more than three times the third" second number = 3x+4 "the first number is 10 less than twice the second" first number = 2(3x+4) - 10 = 6x - 2 " Twice the second number is ...
November 28, 2015

Math
let the time be x years 9+x = (1/4)(42+x) times 4 36 + 4x = 42 + x 3x = 6 x=2 in 2 years check: John will be 44 , nephew will be 11 and 11 is 1/4 of 44
November 27, 2015

Business math
Monthly interest at 7.5 % ? Rather absurd, I would say. Are you sure the rate wasn't compounded monthly?
November 27, 2015

Trigonometry URGENT!
It goes from 125 to 99 in 28 minutes, so a whole cycle or a period would be 56 minutes period = 2π/k = 56 k = 2π/56 = π/28 which automatically rules out a) and c) The sin(anything) has a max of 1 and a min of -1 so 13+112 = 125 -13+112 = 99 So a), b), and c) ...
November 27, 2015

calculus
(e^t + e^-t)² = e^2t + 2 + e^-2t integral (e^t + e^-t)² dx = integral e^2t + 2 + e^-2t dx = (1/2) e^2t + 2t - (1/2)e^-2t + c
November 27, 2015

calculus
Did this for you already http://www.jiskha.com/display.cgi?id=1448624538#1448624538.1448633262
November 27, 2015

Trigonometry
sinØ = 3/5 , Ø in II make a sketch of the corresponding right-angled triangle to see that y = 3, r = 5 x^2 + 3^2 = 5^2 x = ± 4, but we are in II , so x = -4 cosØ = -4/5
November 25, 2015

calc
height = -16t^2 + 72t + 0 so you want the vertex of this parabola t of the vertex = -72/-32 = 2.25 seconds to reach the max height = -16(2.25)^2 + 72(2.25) = 81
November 25, 2015

Geometry
hj = √( (12-2)^2 + (-3-7)^2 ) = √(100 + 100) = √200 = 10√2
November 25, 2015

calc
a(t) = 2t + sin(t) v(t) = t^2 - cos(t) + c given v(0) = 4 4 = 0 - cos 0 + c 4 = -1 + c c = 5 v(t) = t^2 - cos t + 5
November 25, 2015

Pre-Calculus HELP!
compared to f(x) = sinx 15 sinx has its amplitude changed from 1 to 15 sinx + 15 simply shifts sinx up 15 units. You had the last one correct see the graphs here: http://www.wolframalpha.com/input/?i=plot+y+%3D+sinx+%2C+y+%3D+15sinx+%2C+y+%3D+sinx+%2B+15
November 25, 2015

Math
mass of red --- x mass of green --y mass of box ---z 5x + 3y + z = 43 3x + 5y + z = 37 x + y + z = 19 subtract the first two: 2x - 2y = 6 x - y = 3 subtract the last from the first: 4x + 2y = 24 2x + y = 12 Add the two x , y equations: 3x = 15 x = 5 in 2x+y = 12 ---> 10+y...
November 25, 2015

precal
3sin3x+2=4 3 sin 3x = 2 sin 3x = 2/3, so 3x is in I or in II reference angle = 41.81..° so 3x = 41.81 or 3x = 138.19° x = 13.937° or x = 46.063° for more angles add/subtract 120° to each answer to obtain as many solutions as you want.
November 25, 2015

precal
simplify the left side into x's sin 4x = 2sin 2x cos 2x = 4sinx cosx(cos^2x - sin^2x) = 4cos^3 x sinx - 4sin^2 x cosx = almost the right side I suspect a typo
November 25, 2015

Calculus 1
estimate as a trapezoid: height at x =2 is 1/8 height at x=5 = 1/125 average height = (1/8+1/125)/2 = 133/2000 appr area = (3)(133/2000) = 399/2000 = appr .2 actual area = ∫1/x^3 dx from 2 to 5 = ( - 1/(2x^2) ) from 2 to 5 = (-1/2)( 1/25 - 1/4) = 21/200 = .105
November 25, 2015

Calculus 1
Isn't Wolfram neat ? http://www.wolframalpha.com/input/?i=integral+cube+root%28x%29+dx+from+1+to+27 area = ∫x^(1/3) dx from 1 to 27 = (3/4)x^(4/3) from 1 to 27 = (3/4)( 81 - 1) = 60
November 25, 2015

algebra
width ---- x length ----2x+5 solve for x 2x + 2(x+5) = 66
November 25, 2015

algebra
same type of question as the one above, just change the numbers.
November 25, 2015

Algebra
base of box will be 6-2x by 14-2x , where 0 < x < 3 x(6-2x)(14-2x) = 40 x(2)(3-x)(2)(7-x) = 40 x(3-x)(7-x) = 10 x^3 - 10x^2 + 21x - 10 = 0 tried x = ±1, ±2, ±3 x = 2 worked by synthetic division, (x-2)(x^2 - 8x + 5) = 0 x = 2, the other roots are ...
November 25, 2015

Algebra
"the width across the page is four units of the length?" --- don't know what that means
November 25, 2015

Math
I am the product of 135 and ???? decreased by 500. who am I? you need 2 multipliers to have a "product"
November 25, 2015

math
V = (4/3)π r^3 dV/dt = 4π r^2 dr/dt 20 = 4π (36) dr/dt dr/dt = 20/(144π) cm/s = 5/(36π) cm/s
November 25, 2015

Mathematics
Don't rule out m = -10 as extraneous, since they do satisfy the given conditionn. of m = -10, m+8 = -2 their product = (-10)(-1) = 20 -2 is 8 more than -10 the numbers could also be -2 and -10
November 25, 2015

math
Using only one variable: seven years ago: Cora --- x Mary --- 6x present ages: Cora = x+7 Mary = 6x+7 one year from now Cora = x+8 Mary = 6x+8 6x+8 = 2(x+8) 6x +8 = 2x+16 4x=8 x =2 present ages: Cora = x+7 = 9 Mary = 6x+7 = 19
November 25, 2015

Maths
return on 1/3 of the 60000 investment with 20% profit = (1/3)(1.2)(60,000) = 24800 return on 2/3 of investment with a 5% loss = (2/3)(.95(60000) = 38000 total return = 62000 profit percentage = 2000/60000 = 1/30 = .03333.... or 3 1/3%
November 25, 2015

Trigonomtry
correct
November 24, 2015

MATH HELP
y = x^2 + 6 looks like this: http://www.wolframalpha.com/input/?i=y+%3D+x%5E2+%2B+6 now let's look at y = 3x^2 + 6 and y = (4/5)x^2 + 6 on the same grid http://www.wolframalpha.com/input/?i=y+%3D+3x%5E2+%2B+6%2C+y%3D%284%2F5%29x%5E2+%2B+6 what do you think?
November 24, 2015

Algebra
P(x) = R(x) - C(x) = .4x^2 - 29x + 44 +.6x^2 - 19x = x^2 - 48x + 44 this parabola cuts the x-axis at x = 47.065 and a negative Since x represents pencils, x>0 So this parabola will be above the x-axis for x>47 x of vertex is -b/(2a) = 48/2 = 24 P(24) = -532 the vertex is...
November 24, 2015

correction - Math
time taken by Gab ---- x minutes time taken by Van ---- 2x minutes Gab's rate = 1/x Van's rate = 1/2x combined rate = 1/x + 1/(2x) = 3/(2x) so 1/(3/2x) = 40 2x/3 = 40 2x = 120 x = 60 Gab's time alone is 60 minutes, Van's time alone is 120 minutes check: ...
November 24, 2015

Algebra 1- Please help whenever you get the chance
872(.16) + 24.54 = 164.06
November 24, 2015

Math
numerator --- x denominator --- y x/y = 2/3 2y = 3x y = 3x/2 new fraction: (x+4)/(y-2) = 6/7 6y - 12 = 7x + 28 6y = 7x + 40 3(2y) = 7x+40 3(3x) = 7x + 40 2x = 40 x = 20 y = 30 the non-reduced fraction was 20/30
November 24, 2015

Algebra
noticed a silly typo in 4th-last line should say: x= (9/2)(6) = 27
November 24, 2015

Algebra
the x = kx when x=9 , then y=2 9 = 2k k = 9/2 when y=6 x=x(9/2)(6) = 27 or, by simple ratio: x/9 = 6/2 = 3 x = 9(3) = 27
November 24, 2015

math
your school subject is : math not: Abubakar tafawa balewa university bauchi ATBU y = x + (1-x)^(1/2) y' = 1 + (1/2)(1-x)^(-1/2)(-1) = 1 - (1/2)(1-x)^(-1/2) = 0 for a max/min 1 = (1/2) (1/√(1-x) √(1-x) = 1/2 1-x = 1/4 4-4x=1 x = 3/4 f(3/4) = 3/4 + √(1-3/4...
November 24, 2015

math
4 years ago: Fe : --- x Jim: --- 4x Now: Fe = x+4 Jim = 4x+4 4 years from now: Fe = x+8 Jim = 4x + 8 4x+8 = 2(x+8) 4x + 8 = 2x + 16 2x = 8 x = 4 Now, Fe is 8 and Jim is 20
November 23, 2015

Math
looks like just sin5° = 1250/hyp where hyp is the hypotenuse you want hyp = 1250/sin5° = ...
November 23, 2015

Algebra 2
from the standard version of this form, vertex is (-20,0) axis of symmetry: x -20 min is 0 domain: any real number range: any real number, y≥0
November 23, 2015

Algebra
one number --- x the other ------2x+58 their product = x(2x+58) their sum = 3x + 58 x(2x+58)= 2(3x+58) + 58 2x^2 + 58x = 6x + 116 + 58 2x^2 + 52x - 174 = 0 (x-3)(2x + 58) = 0 x = 3 or x = -58/2 = -29 if x = 3 one number is 3, the other is 64 if x = -29 one number is = -29, the...
November 23, 2015

math
I am not familiar with the stock-market system in your country, but I can do the 2nd question rate of first pipe = 1/x cisterns/min rate of 2nd pipe = 1/(x+5) cisterns/min combined rate = 1/x + 1/(x+5) = (x+5 + x)/(x(x+5)) but that is 11 1/9 min or 100/9 minutes 1/[(2x+5)/(x(x...
November 23, 2015

Calculus
just did a question just like yours http://www.jiskha.com/display.cgi?id=1448296657 follow the steps for the half life, set the amount = 50 and solve for t
November 23, 2015

Pre-calculus
so 600(.97) = 600 e^(7k) .97 = e^(7k) ln .97 = 7k lne 7k = ln .97 k = ln .97/7 = -.004351315 amount = 600 e^-.0043511315t so when t = 24 amount = 600 e^-.104431.. = .900836(600) ----> 90.08% remain = 540.50 mg
November 23, 2015

Math
Since when does 42 lie between 25 and 36 ???
November 23, 2015

precalc
10^-2/3 = ....
November 23, 2015

math
choose 2 of the 6 meats and one of the 3 cheeses number of combinations = C(6,2) x C(3,1) = 15(3) = 45
November 23, 2015

math
Area to be covered = 42(80) or 3360 f^2 number of bags = 3360/350 = 9.6 but you can't buy a partial bag, so he needs 10 bags, which will cost $78.90
November 23, 2015

math
makes no sense! How can an amount (money I assume) be less if there is positive interest rate ?
November 23, 2015

calculas
Let the radius of the water level be r cm let the height of the water be h cm by ratio: r/h = 4/16 = 1/4 h = 4r or r = h/4 V = (1/3)π r^2 h = (1/3)π (h^2/16)(h) = (1/48)π r^3 dV/dt = (1/16)π r^2 dr/dt a) for the given data: .3 = (1/16)π(25) dr/dt dr/dt...
November 23, 2015

Statistics
Since you have the mean and sd plug in your range into http://davidmlane.com/hyperstat/z_table.html (one of the best sites for replacing all those nasty tables in the back of your text)
November 23, 2015

Math
you have contradictory and un-needed information, if a = -16 and r = 7 term(5) = ar^4 = -16(7^4) = - 38416 I suspect a typo anyhow, we won't need that anyway sum(5) = a(r^5 - 1)/(r-1) = -16(7^5 - 1)/6 = -44816
November 22, 2015

Math
looks like an AS with a = 12.1 , d = .9 what is the term number of 32.8 ? a + (n-1)d = termn 12.1 + (n-1)(.9) = 32.8 .9n- .9 = 20.7 .9n =21.6 n = 24 sum(24) = 12(first + last) = 12(12.1 + 32.8) = 538.8 check my arithmetic
November 22, 2015

probability
ok, I misread the question. All Cases , where X is not blue, 2 blue, 6 non-blue BBB --- not possible, only 2 blue BBX BXB ---> (2/8)(6/7)(1/6) = 1/28 XBB ---> (6/8)(2/7)(1/6) = 1/28 BXX XBX XXB ---> (6/8)(5/7)(2/6) = 5/28 XXX your prob = 7/28
November 22, 2015

probability
So you want the sequence XXB , that is, notblue-notblue-blue prob = (6/8)(5/7)(2/6) = 5/28
November 22, 2015

Math
using the formulas for GP's a = 25 ar^5 = -1/125 r^5 = (-1/125)(1/25) = -1/3125 r = (-1/3125)^(1/5) = -1/5 term3 = ar^2 = 25(-1/5)^2 = 1
November 22, 2015

Math
Notice that when you double the first equation (line), you get the second equation. Thus you have really one equation. So there would be an infinite number of solutions, that is, any point on the line is a solution If the second equation would have been 10x - 4y = 5, you would...
November 22, 2015

Calculus
see http://www.jiskha.com/display.cgi?id=1448204036 you did not answer Damon's question.
November 22, 2015

Algebra
Your setup is sloppy let the first number be x then the second number is 3x and the third is 3x+5 now translate the following: "if the second is decreased by twice the third number, the result is five" ----> 3x - 2(3x+5) = 5 3x - 6x - 10 = 5 -3x = 15 x = -5 check...
November 22, 2015

Math
since we know the x-intercepts, we can say y = a(x-1)(x-3) but (-1,16) lies on it, so 16 = a(-2)(-4) 16 = 8a a = 2 y = 2(x-1)(x-3) or y = 2x^2 -8x + 6
November 22, 2015

math
Volume of full tank = 5^3= 125 m^3 If 1/5 of it is empty, then 4/5 of it is full What is (4/5)(125) ? #2 Let P be (x,y) so that AP is the shorter segment to get the x: (x+2)/(3-x) = 2/3 3x + 6 = 6 - 2x 5x = 0 x = 0 to get the y: (y-6)/(-4-y) = 2/3 3y - 18 = -8 - 2y 5y = 10 y...
November 22, 2015

math
SA = 2 circles + a rectangle = 2πr^2 + 2πrh 440 = 2π(49) + 2π(7)h h = (440- 98π)/(14π) = ... you do the button-pushing, should get appr 3m
November 22, 2015

math
you have an arithmetic sequence with a = 5,000,000,000 d = -10 n = ?? , where n is in seconds term(n) = a+(n-1)d you want term(n) = 0 5,000,000,000 + (n-1)(-10) = 0 -10n + 10 = -5000000000 -10n = -5,000,000,010 n = 500,000,001 seconds = 8,333,333.35 minutes = 138,888.89 hours...
November 22, 2015

math
greens ---- x reds ------ 8x x + 8x + 36 take over, it's a piece of cake.
November 22, 2015

calculas
V = (4/3)π r^3 dV/dt = 4π r^2 dr/dt -4 = 4π r^2 dr/dt (-4 because V is decreasing) dr/dt = -1/(πr^2) S = 4π r^2 dS/dt = 8πr dr/dt = 8πr(-1/(π r^2) = -8/r so when r = 24 , dS/st = -8/24 = -1/3 The surface area is decreasing at 1/3 cm^2 ...
November 22, 2015

math
smallest 2 digit number divisible by 4 is 12 so we want: 12, 16, 20, 24, 28, 32, 36, 40,.... ,96 this is an arithmetic sequence with a = 12, d=4 what term number is 96 ? a + (n-1)d = 96 12 + (n-1)(4) = 96 4n - 4 = 84 4n = 88 n = 22 There would be 22 terms divisible by 4 BUT, ...
November 22, 2015

Algebra 1
Tylers rate = 1/x kitchens/hr Mary's rate = 1/9 kitchens /hr combined rate = 1/5 but combined rate = 1/x + 1/9 = (9+x)/(9x) = 1/5 9x = 45+5x 4x=45 x = 45/4 = 11.25 hrs Alone would take him 11.25 hrs
November 21, 2015

math 1350
so does 315
November 21, 2015

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