Question

To collect data on the signal strengths in a neighborhood, Briana must drive from house to house and take readings. She has a graduate student, Henry, to assist her. Briana figures it would take her 12 hours to complete the task working alone, and that it would take Henry 18 hours if he completed the task by himself. How long will it take Briana and Henry to complete the task together?

Answer 1

Both take time together = 36 / 5 hours = 7.2 hours

Explanation:

Given:

Briana take time = 12 hour

Henry take time = 18 hour

Find:

Both take time together

Computation:

Briana 1 hour work = 1/12

Henry 1 hour work = 1/18

Both take time together = 1/[1/12+1/18]

Both take time together = 1/[5/36]

Both take time together = 36 / 5 hours = 7.2 hours