Question

For a week, the average daily rainfall was $0.25cm$. There was no rainfall on Saturday. Rainfall on Sunday, Monday, Tuesday, Wednesday and Thursday was $0.4cm,0.03cm,0.45cm,0.27cm$and $0.5cm$ respectively. What was the rainfall on Friday?

• A. $0.2$ cm
• B. $0.1$ cm
• C. $0.05$ cm
• D. $0.015$ cm

Answer 1

The correct option is B $0.1$ cm

Average is the sum of the data values divided by the total number of data values.

Given that average rainfall for a week is $0.25$ cm

Let the rainfall on Friday be $x$

Given that, rainfall on Sunday, Monday, Tuesday, Wednesday, Thursday and Saturday are $0.4$ cm, $0.03$ cm., $0.45$ cm., $0.27$ cm., $0.5$ cm. and $0$ cm. respectively.

Therefore, $average=\frac{0.4+0.03+0.45+0.27+0.5+0+x}{7}=0.25$

$⟹\frac{1.65+x}{7}=0.25$

$⟹1.65+x=0.25\times 7=1.75$

$⟹x=1.75-1.65=0.1$

Therefore, the average rainfall on Friday is $0.1$ cm.