Shankar travelled from P to Q at an average speed of 50 km/hr. He travelled the first 60% of the distance in two-thirds of the total time, and the rest at a constant speed of \(x\) km/hr. What is the value of \(x\)?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 60
Average speed \(=\) total distance \(\div\) total time. The last 40% of the distance is covered in the last one-third of the time.
Let the distance be \(D\) km and the time \(T\) hours, with \(\displaystyle \frac{D}{T}=50\)
Last part: distance \(0.4D\) in time \(\displaystyle \frac{T}{3}\)
\(\displaystyle x=\frac{0.4D}{T/3}=1.2\times\frac{D}{T}=1.2\times50=60\)
The value of \(x\) is 60.