SOLUTION: Three brothers,Michael,Matthew and Mark are tasked to mow a 2000 square meter garden. In 8 hours, Michael, the eldest, can mow 1200 square meters. Matthew can mow 600 square and Ma

Question 919280: Three brothers,Michael,Matthew and Mark are tasked to mow a 2000 square meter garden. In 8 hours, Michael, the eldest, can mow 1200 square meters. Matthew can mow 600 square and Mark, the youngest ca mow 200 square meters. If they work together for 5 hours, what part of the garden is not mowed?

Follow up question: with reference to the question above, suppose the three brothers worked together for 4 hours but Mark got tired and quit. Matthew stayed for another half-hour and quit. How long will it take Michael to finish the job?
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
lawn to be mowed is 2000 square meters.

michael can mow 1200 square meters in 8 hours.
his rate of mowing is therefore 1200 / 8 = 150 square meters per hour.

matthew can mow 600 square meters in 8 hours.
his rate of mowing is therefore = 600 / 8 = 75 square meters per hour.

mark can mow 200 square meters in 8 hours.
his rate of mowing is therefore = 200 / 8 = 25 square meters per hour.

when they work together, their rates are additive.

since rate * time = quantity, then you get:

(150 + 75 + 25) * time = 2000 square meters.

simplify by combining like terms to get:

250 * time = 2000 square meters.

divide both sides of the equation by 250 to get time = 2000 / 250 = 8 hours.

working together, they will be able to mow the the whole lawn in 8 hours.

in 5 hours, they will be able to mow 5/8 * 2000 = 1250 square meters.

looked at another way, their combined rate is 250 square meters per hour.

multiply that by 5 and you get 5 * 250 = 1250 square meters.

since the lawn is 2000 square meters and they mow 1250 square meters in 5 hours, then what is left ot mow is 750 square meters.

RELATED QUESTIONS
Three brothers,Michael,Matthew and Mark are tasked to mow a 2000 square meter garden. In... (answered by Edwin McCravy)

Three brothers,Michael,Matthew and... (answered by richwmiller)

Michael can mow the lawn in half an hour, and Alex can mow it in three quarters of an... (answered by josgarithmetic)

Mr. Agbuya can mow a lawn in 3hours. His sons, Michael and Arnel can each do the job in... (answered by macston)

Michael can do a job 3 hours faster than Dennis. Together they can complete the work in 8 (answered by BlGDAVE,josgarithmetic)

41. Mr. Agbuya can mow a lawn in 3 hours. His sons, Michael and Ariel, can each do the... (answered by Edwin McCravy)

Michael can mow 2/5 of his yard in one hour. How many hours would it take for Michael... (answered by CubeyThePenguin,ikleyn,greenestamps,josgarithmetic)

sammy can mow a lawn in 3 hours. his two young brothers can each do the job in 2 hours.... (answered by KMST)

sammy can mow a lawn in 3 hours. his two young brothers can each do the job in 2 hours.... (answered by alma11,Alan3354)