Dwight and Mose decide to build a new barn on their farm,

swerve wrote:Dwight and Mose decide to build a new barn on their farm, and they begin to work in alternating shifts, with Dwight taking the first shift. During each of his shifts, Dwight does 1/4 of the remaining work. During each of his shifts, Mose does 1/6 of the remaining work. How much of the barn is left to finish when Mose begins his third shift?

A. 1/24
B. 5/36
C. 25/72
D. 75/26
E. 255/512

The OA is D

Source: Veritas Prep

The best way to solve this problem is to keep track of the fraction of the barn that still needs to be completed after each of their shifts:

Dwight’s 1st shift: 1/4

Fraction of the barn still needs to be completed: 3/4

Mose’s 1st shift: 1/6(3/4) = 1/8

Fraction of the barn still needs to be completed: 5/6(3/4) = 5/8

Dwight’s 2nd shift: 1/4(5/8) = 5/32

Fraction of the barn still needs to be completed: 3/4(5/8) = 15/32

Mose’s 2nd shift: 1/6(15/32) = 5/64

Fraction of the barn still needs to be completed: 5/6(15/32) = 25/64

Dwight’s 3rd shift: 1/4(25/64) = 25/256

Fraction of the barn still needs to be completed: 3/4(25/64) = 75/256

We can see that before Mose begins his 3rd shift, 75/256 of the barn still needs to be completed.

Answer: D