Question

Lisa, an experienced shipping clerk can fill an order in 9 hours. Felipe a clerk needs 11 hours to do the same job. Working together how long will it take them to fill the order.

Answer 1

Answer:

4  hours and  57  minutes.

Step-by-step explanation:

The least common multiple of  9  and  11  is  99 .  

In  99  hours, Sue could fill  11 orders (99 divided by 11)

Felipe could fill 9  orders ( 99  divided by 11 ), making a total of  

9 + 11 = 20  orders if they both work.

So for both of them working to fill one order would take:  

99 /20  hours.

To express in hours and minutes:

99 /20 = 80 /20 + 19 /20 = 4 +  3 ⋅ 19 /3 ⋅ 20 = 4 +  57 /60

That's  4  hours and  57  minutes, since a sixtieth of an hour is one minute.