CAT 2021 Question Paper | Quant Slot 1

CAT 2021 Quant was dominated by Arithmetic followed by Algebra. In Arithmetic, the questions were dominated by topics like Speed-time-distance, Mixture and Alligations. This year, there was a surprise. The questions from Geometry were relatively on the lower side as compared to the previous years. There were 8 TITA Qs this year. Overall this section was at a medium level of difficulty.

Question 21 : Two trains cross each other in 14 seconds when running in opposite directions along parallel tracks. The faster train is 160 m long and crosses a lamp post in 12 seconds. If the speed of the other train is 6 km/hr less than the faster one, its length, in m, is

Video Explanation

Explanatory Answer

The faster train is 160 m long and crosses a lamp post in 12 seconds.
The speed of the faster train = \\frac{160}{12}) = \\frac{40}{3}) m/s
Given that, the speed of the other train is 6 km/hr (\\frac{5}{3}) m/s) less than the faster one. [we can convert speeds from km/h to m/s by multiplying with 5/18]
The speed of the slower train = \\frac{35}{3}) m/s.
Given that, the two trains cross each other in 14 seconds when running in opposite directions along parallel tracks.
Relative speed = \\frac{\text { total length of two trains }}{\text { time taken to cross each other }})
25m/s = \\frac{160+\text { length of second train }}{14})
Length of the second train = 190m.

The answer is '190'

Choice C is the correct answer.