Question

Lester and Ralph work at an athletic shoe store in the mall, but whenever they goof off too much, their boss punishes them by making them lace-up all the inventory. I f it takes Lester 30 seconds to lace up a high top and Ralph 35 seconds to do the same, how many seconds will it take them to lace-up 260 high tops?

Answer 1

4200

Explanation:

Time taken by Lester 30 seconds

Time taken by Ralph = 35 seconds

Their rate :

Lester = 1/time taken = 1/30

Ralph = 1/ time taken = 1/35

Combined rate:

1/30 + 1/35 = (35 + 30) / 1050 = 65 / 1050 = 0.0619047 per boot

Time taken = number of boots / combined rate per boot

Time taken = 260 / 0.0619047

Time taken = 4200 seconds