Question

A school has 9 periods of 40 minutes duration in a day. If the working hours of a school remain the same and it changes to 8 periods in a day, then the duration of each period would be?( use the formula of direct or inverse propotion)​

Answer 1

Answer:

Let x minutes be the duration of period when the school has 9 periods a day. Then

Number of periods     8         9

Duration of periods (in minutes)           45 x

Clearly, more the periods, less will be the duration of the period.

So, it is a case of inverse proportion.

∴8×45=9×x

⇒x=  

9

8×45

​  

=40

Hence, the duration of period is 40 minutes

Step-by-step explanation:

Answer 2

Given :

• School has 9 periods of 40 minutes Duration in a Day.

• Working hours remains the same and it changes to 8 periods in a Day.

• Should use the formula of direct or inverse proportion.

To find :

• The Duration of each period would be ?

According to the question :

No. of. Periods Time ( minutes )

9 Periods ⬆️ 40 minutes ⬇️

8 Periods x

For 9 Periods the duration of Time is 40 minutes, So for 8 Periods the duration of Time will increase .

If periods decrease, Time will be increased & If periods increase, Time will be decreased. So It is Inverse Variation / Proportion.

Solving :

⟹ x = 8 / 40 × 9

⟹ x = 5 × 9

⟹ x = 45

The Duration of each period would be 45 Minutes.

Formulas :

↦Direct Proportion / Variation = Cross Multiply.

↦Inverse Proportion / Variation = Crossly Divide.

So It's Done !!