Question

average daily rainfall during first 30 days of July was 1.5 mm. However so much rain fell on 31 July that average daily rainfall for the month of July was 2 mm. What is the rainfall on 31 july

Answer 1

Let the rainfall for 31st july be x

Average rainfall for first 30 days=1.5mm

Total rainfall for 30 days=30×1.5=45mm

Total rainfall for 31days=45+x

Average=(45+x)/31=2

=>45+x=31×2=62

x=62-45=17mm

Hope this helps :)