Question

Jack mows his lawn in 5 hours Marilyn in 3 hours, how long will it take to mow the lawn if they work togethe?







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Answer 1

4 hours

Answer 2

do you like to know how to get that?

Answer 3

yes

Answer 4

Yup, you find the mean of those two numbers.
(5 + 3)/2

Answer 5

Jack mows his lawn in 5 hours Marilyn in 3 hours, how long will it take to mow the lawn if they work togethe?

so in 1 hour, Jack can do 1/5 of the job, Marilyn can do 1/3 of the job

Answer 6

(1/5 + 1/3)h=1

find h

Answer 7

Actually, 4 hours is wrong. The way to think about it is rates.

Jack mows at a rate of 1/5 of a lawn per hour; Marilyn at 1/3 of a lawn per hour.

Hence together, they mow at (1/5 + 1/3) of a lawn per hour

i.e., 8/15 lawn per hour

Thus their combined time is 15/8 hours, or just under 2 hours.

Answer 8

\[\frac{5+3}{5 \dot\ 3} \]