A train leaves station P at 6 AM and reaches station Q at 10 AM. At the same time (i.e. at 6 AM) another train leaves station Q and reaches station P at 9.30 AM. The two trains cross each other at

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This question was previously asked in

UGC NET Official Paper 1: Held On 19 June 2023 Shift 1

Answer 1

Concept used:

Time = Distance/Speed

Calculation:

Let's assume that the total distance be D, so the speed of train A = D/4 and the speed of train B = D/3.5

Now, two trains are moving in opposite directions, relative speed be (D/4 + D/3.5)

Time takes to meet = \(\frac{D}{\frac{D}{4}+\frac{D}{3.5}}\) = \(\frac{D}{\frac{D}{4}+\frac{2D}{7}}\) = \(\frac{28D}{15D}\) = 28/15 hr = 112 min

So, two trains cross each other at 6 AM + 112 min = 7 AM + 52 min = 07 : 52 AM

∴ The correct answer is 07 : 52 AM