Question

If two cars $A$ and $B$ move towards each other, where car $A$ starts at $9$ a.m. and $B$ at $10$ a.m. The speeds of the car $A$ and $B$ are $40$ km/hr and $50$ km/hr respectively. what distance does car travel when the two cars meet, if the initial distance between $A$ and $B$ is $400$ km?

• A. $100$ km
• B. $200$ km
• C. $300$ km
• D. $400$ km

Answer 1

The correct option is B $200$ km

Let $t$ hrs. be the time taken by the car $B$ to reach the crossing point
Hence, $A$ will take $(t+1)$ hrs. to reach the same point
Speed of car $B=50$ km/hr
Distance covered before the crossing $=50$ $\times$ $t$
Now using the strategy (4), we know that the total distance covered by the two cars is the total distance between their starting points.
i.e. $40(t+1)+50t=400$
$\Rightarrow$ $40t+50t+40=400$
$\Rightarrow$ $90t=360$
$\Rightarrow$ $t=4$ hrs
Hence, the distance covered by car $B=50$ $\times$ $4=200$ km.