Question

Distance between two points A and B is 110 km A motor cycle rider starts from A towards B at 7 am at a speed of 20 km/hr. Another motor cycle rider starts from B towards A at 8 am at a speed of 25 km/hr. Find when will they cross each other.

• A. 11 am
• B. 9 : 30 am
• C. 8 : 30 am
• D. 10 am

Answer 1

Answer: (D)

10 am

The distance from A to B $=110$km.

The biker from A starts at $7am$.

So by 8 am he travels for $1hr$.

His speed $=20km/hr$.

Then the distance covered form $7am$ to $8am=20km$.

Rest of the distance $=(110-20)km=90$km.

Now the biker from B starts.

Their relative speed $=(20+25)km/hr.=45$km/hr.

(since they are approaching each other.)

So, the time taken=$\frac{distance}{relativespeed}=\frac{90}{45}$hrs.=2hrs.

So they will meet each other after $3$ hrs from$7am$

i.e at $10am$.