Question

Anuj takes $15$ minutes to go the school and $20$ minutes to come back form the school by bicycle. If school is $4.5$ km away form home, find his average speed.

Answer 1

Speed while going to school$=\frac{distance}{time}$

$=\frac{4.5}{15\times 60}$

$=\frac{45}{15\times 600}=\frac{1}{200}$

$V_1=\frac{1}{200}$

Speed while returning$=\frac{distance}{time}=\frac{4.5}{20\times 60}$

$V_2=\frac{45}{20\times 600}=\frac{3}{800}$

Average speed$=\frac{V_1+V_2}{2}$

$=\frac{\frac{1}{200}+\frac{3}{800}}{2}=\frac{\frac{4+3}{800}}{2}=\frac{7}{1600}$