Question

$15$ persons complete a work in $4$ days by working $6$ hours a day. How many days will it take to complete the work if $10$ persons work $8$ hours a day?

• A. $12$
• B. $4.5$
• C. $3$
• D. $9$

Answer 1

The correct option is B $4.5$

No of person is inversely proportional to the no of days.
Again, no of hours is inversely proportional to the no of days.
So, $15\times 4=k=5\times x$
$\Rightarrow x=12$; taking no of hours per day constant.
$15\times 4=k=10\times 4$
$\Rightarrow x=6$ taking no of hours per day constant
Again $6\times 6=y\times 8$; taking no of person constant.
$\Rightarrow y=\frac{36}{8}=4.5$