Arithmetic reasoning lawnmowers

Question

Suppose mark can mow the entire lawn in 47 minutes, and marks dad can mow the entire lawn in 53 minutes. If mark and his dad work together ( each mower) , how long will it take them to mow the entire lawn?

Answer 1

t represents the time that they work together

(t / 47) + (t / 53) = 1

53t + 47t + (47)(53)

Can you solve for t and answer?

Answer 2

Mark does the lawn in 47 min. So Mark does 1/47th of the lawn in 1 min.

Dad does it in 53 min. So Dad does 1/53rd of the lawn in 1 min.

Formula: 1/Dad = 1/Mark = 1/Together

1/47 + 1/53 = (53 + 47)/2491=100/2491

1/(100/2491) = 2491/100 = 24.9 min. if they both work.

Or solve as a proportion: 100/2491 = 1/ together Cross mult to solve; 100T = 2491 -> T = 2491/100 = 24.9 min.

Can also do it using decimal equivalents (easier math?)

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