Question

Bobby has a party while his parents are away for the weekend. Bobby estimated that if his 9 friends hep him to clean the house, they will finish in time if they start 8 hours before his parents return. But after only two hours of cleaning, Bobby's parents call and say they are just two hours from home. How many more friends does Bobby need to call to help finish cleaning in time.

Answer 1

Bobby will need additional 20 friends to help finish cleaning in time.

Rate at which Bobby and his 9 friends are working

The rate at which Bobby and his 9 friends are cleaning the house is determined as follows;

10 person ------> 8 hours

1 person -------->?

= 10 x 8 = 80 hours/person

When the parents are 2 hours from the house, Bobby will more friends working at the same rate to complete it in 2 hours time.

During this period Bobby and his friends have worked for 2 hours remaining 6 hours.

New rate;

10 person ------> 6 hours

1 person -------->?

1 person = 10 x 6 hrs = 60 hours per person

Total persons that will do the same work in 2 hours

2 = 60/x

x = 60/2

x = 30 persons

Thus, Bobby will need additional 20 friends to help finish cleaning in time.

Learn more about rate of work here: https://brainly.com/question/1144815

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