Question

A man starts from B to K, another from K to B at the same time. after passing each other they complete their journey in $3\frac{1}{3}$ and $4\frac{4}{5}$ hours respectively. Find the speed of the second man if the speed of the first is $12$ km/h ?

• A. $10$ kmph
• B. $12$ kmph
• C. $15$ kmph
• D. $20$ kmph

Answer 1

The correct option is A $10$ kmph

Step 1

Let them meet at point C. So after meeting at point C, they take $3_3^1$ & $4_5^4$ hours to reach their destinations.

Lt the time taken be t before meeting.

Step 2

The speed of first man is $12km/h$

let the speed of second man be $xkm/h$

Step 3

So $BC=12t=\frac{24}{5}\times x$

$CK=\frac{10}{3}\times 12=xt$

Step 4

Dividing both. $\frac{12t}{40}=\frac{24x}{5xt}$

$={60t}^2=24\times 40$

$t=4$ hours

$\therefore x=10km/h$