If it takes Cynthia 6 hours to read a book and Mandy 7 hours to read a book how long would it take if they read worked together

Question

it takes cynthia 6 hours to proof a chapter of hawkes learning systems introductory algebra books and it takes mandy 7 hours how long would it take them working together

Answer 1

cynthia can do 1/6 of the job per hour and mandy can do 1/7 of the job per hour

 

they can work together if the have different books

 

1/6h+1/7h=1

 

(1/6+1/7)h = 1

 

13/42h=1

 

h =42/13 hours

Answer 2

Again this nonsensical problem shows up.  Nonsensical because because to read a book "together", each individual must be present. If they read silently, then it takes 7 hours (time dictated by the slower reader).

 

If they read aloud, alternating so that only one person speaks at a given time, then they must both be present to hear the full book, so it takes somewhere between 6 and 7 hours to accomplish this.

 

Anything else deprives the two persons the opportunity to understand the full content of the book, which is of course the criterion by which "having read a book" is judged.

 

As before, I suspect that this problem comes from the Common Core world, where sensibleness of problems is not guaranteed because of the rush to market materials that have been poorly vetted.

 

Share these observations, please, with your teacher and parents.