Problema Solution
Jeff and Kirk can build a 75-ft retaining wall together in 3 hours. Because Jeff has more experience, he could build the wall by himself 3 hours quicker than Kirk. How long would it take Kirk (to the nearest minute) to build the wall by himself?
Answer provided by our tutors
let
x = the hours that Jeff needs to build the wall alone thus his rate is 1/x walls per hour, x>0
x + 3 = the hours that Kirk need to build the wall alone this his rate is 1/(x + 3) walls per hour
Jeff and Kirk can build a 75-ft retaining wall together in 3 hours follows their together rate is 1/3 walls per hour
1/x + 1/(x + 3) = 1/3
by solving we find:
x = 4.854 hr
click here to see the step by step solution of the equation:
x = 4 hr 0.854*60 min
X = 4 hr 51 min
Kirk will need 4 hr 51 min to build the wall alone.