Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 3 hours. How much time would it take for them to mow the lawn together?

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Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 3 hours. How much time would it take for them to mow the lawn together?

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Answer 1 · 2017-12-07T00:17:11

1.875hours

Explanation:

First, remember that $Q = (q u a n t i t y) = r (r a t e) \times t (t i m e)$ $Q=(quantity)=r(rate)xxt(time)$

From this, we can set up a table: enter image source here

From this, we know that $\frac{1}{5} + \frac{1}{3} = \frac{1}{t}$ $1/5+1/3=1/t$

To solve this, we find the LCM of 5,3, and t.
The LCM of 5,3,and t is 15t.

We turn the fraction in the equatoin so they all have the denominator of 15t.

$\frac{1}{5} + \frac{1}{3} = \frac{1}{t}$ $1/5+1/3=1/t$ becomes
$\frac{3 t}{15 t} + \frac{5 t}{15 t} = \frac{15}{15 t}$ $(3t)/(15t)+(5t)/(15t)=15/(15t)$
$\frac{3 t + 5 t}{15 t} = \frac{15}{15 t}$ $(3t+5t)/(15t)=15/(15t)$
$\frac{8 t}{15 t} = \frac{15}{15 t}$ $(8t)/(15t)=15/(15t)$
$120 t^{2} = 225 t$ $120t^2=225t$
$120 t = 225$ $120t=225$
$t = \frac{15}{8}$ $t=15/8$

Therefore, together, it takes 1.875 hours to mow the lawn.

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Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 3 hours. How much time would it take for them to mow the lawn together?

1 Answer

Explanation:

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Impact of this question

Science

Math

Humanities

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Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 3 hours. How much time would it take for them to mow the lawn​ together?

1 Answer

Explanation:

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Impact of this question

Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 3 hours. How much time would it take for them to mow the lawn together?