Question

Frank can build a fence in twice the time it would take Sandy. Working together, they can build it in 7 hours. How long will it take each of them to do it alone? ​

Answer 1

QUESTION :-

=> Frank can build a fence in twice the time it would take Sandy. Working together, they can build it in 7 hours. How long will it take each of them to do it alone.

SOLUTION :-

=> If Frank and Sandy can build the fence in 7 hours, they must be building 1/7 of the fence every hour.

=>Now, let the amount of time it takes Sandy be x hours so that Frank takes 2x hours. Sandy can build 1/x of the fence every hour and Frank can build 1/2x of the fence every hour.

=> We now have the following equation to solve.

=> 1/x + 1/2x = 1/7

=> 2 +1 /2x = 1/7

=> 3/2x = 1/7

=> 2x = 21

=> x = 21/2

=> .°. x = 10.5 .

Thus, Sandy takes 10.5 hours and Frank takes 21 hours.