Question

Helpp pLZZZZ

Jack can mow the baseball grounds in 2 hours; Mike can mow the same grounds in 3 hours; and Chris can mow the grounds in 4 hours. How long will it take to mow the baseball grounds if Jack, Mike, and Chris work together?
Leave your answer in proper fraction form, then round to 1 decimal place.
Using your rounded answer, how many minutes would that be?

Answer 1

1hr 37min 18 sec

Explanation:

Jack can mow the baseball grounds in 6 hours

Jack rate = 1/6 job/hr

-------------------------------

Mike can mow the same grounds in 5 hours

Mike rate = 1/5 job/hr

-------------------------------

Chris can mow the grounds in 4 hours.

Chris rate = 1/4 job/hr

-------------------------------

Together rate = 1/x job/hr

----------------------------------

Equation:

rate + rate + rate = together rate

[ 1/6 + 1/5 + 1/4] = 1/x

x[(5*4 + 6*4+ 6*5)/(6*5*4)] = 1

----

x(74/120) = 1

x = 120/74 = 1.62 hours = 1 hr 37 min 18 sec