Question

Two trains started at 7AM from the same point. The first train travelled north at a speed of 80 km/h and the second train travelled south at a speed of 100 km/h. The time at which they were 540 km apart is____AM

• A.
  $9$
• B.
  $10$
• C.
  $11$
• D.
  $11:30$

Answer 1

The correct option is B

$10$
According to the concept of relative speed in opposite direction speeds should be added
$Timeofactivity=\frac{Sumofdistance}{Sumofspeeds}$

$=\frac{540}{100+80}=\frac{540}{180}$

$=3hoursfrom7am=10am$