Question

Two boys $A$ and $B$ start at the same time to ride from Delhi to Palwal, $60km$ away. A travels $4km$ an hour slower than $B$. $B$ reaches Palwal and at once turns back meeting $A12km$ from Palwal. The rate of speed of $A$ was

• A. $4km/hr$
• B. $8km/hr$
• C. $12km/hr$
• D. $16km/hr$
• E. $20km/hr$

Answer 1

The correct option is B $8km/hr$

Notice that $A$ and $B$ both travel for the same amount of time. Since $A$ travels $48$ miles while $B$ travels $72$ miles, we have
$t=\frac{48}{r}=\frac{72}{r+4};\therefore r=8$.