Question

A school has $8$ periods a day each of $45$ minutes duration. How long would each period be, if the school has $9$ periods a day, assuming the number of school hours to be the same?

• A. $32$ minutes
• B. $40$ minutes
• C. $45$ minutes
• D. $20$ minutes

Answer 1

The correct option is B $40$ minutes

For fixed school hours an increase in duration of a period means a decrease in number of periods.Thus the two are variables are in inverse proportion.
Duration of each period $45$ $d$
Number of period $8$ $9$
$\Rightarrow 45\times 8=d\times 9$
$\Rightarrow d=45\times 8÷9=40$
Thus the duration of each period will be $40$ minutes.