Question

Correct0It takes Kim 7 hours to proof a chapter of Hawkes Learning Systems Introductory Algebra book and it takes Harding 2 hours. How long would it take them workingtogether? (Round your answer to two decimal places.)

Answer 1

1.56 hours

Step-by-step explanation

If Kim reads 1 chapter in 7 hours, in 1 hour she would read,

`(1chapter)/(7h)=(1)/(7)chapter/hour`

Similarly, if Harding reads the same chapter in 2 hours, then in 1 hour he will read,

`(1chapter)/(2h)=(1)/(2)chapter/hour`

If they work together, in 1 hour they would read,

`(1)/(7)chapter+(1)/(2)chapter=(2+7)/(2\cdot7)chapter=(9)/(14)chapter`

If they read together 9/14 of a chapter in 1 hour, then they will read 1 full chapter in,

`1chapter\cdot(1h)/((9)/(14)chapter)=(14)/(9)h\approx1.56h`

Hence, if they work together, they will read the chapter in 1.56 hours.