Question
Ron and Benny take 4 days to assemble a toy plane. Benny and Jerry take 6 days to build the same toy plane while Ron and Jerry take only 3 days. How long would the three of them take to build the same toy plane?
Answers
oobleck
1/r + 1/b = 1/4
1/b + 1/j = 1/6
1/r + 1/j = 1/3
adding all three equations and dividing by 2, we get
1/r + 1/b + 1/j = 3/8 = 1/N
so it will take them N = 8/3 days
1/b + 1/j = 1/6
1/r + 1/j = 1/3
adding all three equations and dividing by 2, we get
1/r + 1/b + 1/j = 3/8 = 1/N
so it will take them N = 8/3 days