If Jim Roller can paint a room in 3 hours while John Brush would take 5 hours, how long will they take if they work together? 1/8 hour

Question

asked Jul 16, 2019 172k views

2 Answers

Knut Saua Mathiesen · Answer 1 · 2019-07-22T08:12:53+0000

Answer:
$1(7)/(8)\ hours$

Explanation:

If they are working alone

Jim does of the job in 1 hour=
(1)/(3) of work

John does of the job in 1 hour=
(1)/(5) of work

Let x be the number of hours to do the job if they work together.

Thus, each hour, they do
(1)/(x) of the job when they work together.

According to the question,

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

$\Rightarrow(1)/(x)=(5+3)/(15)\\\Rightarrow(1)/(x)=(8)/(15)\\\Rightarrow\ x=(15)/(8)=1(7)/(8)\ hours$

∴ The number of hours to do the job if they work together=
$1(7)/(8)\ hours$