RRB Group D 22-Sep-2018 Shift 1 Solved Paper

Question : 70 of 100

Marks: +1, -0

A train travelling at constant speed crosses two persons walking in the same direction in 8 seconds and 8.4 seconds respectively. The first person was walking at the speed of 4.5 km/hr while the second was walking at the speed of 6 km/hr. What was the speed of the train in km/hr?

Validate

Solution:

Let length of train is

L \ { km},

speed is

' S' \ {km} \/ {hr}

{L}/{S-4.5}={8}/{60 \×60} \ {km} \/ {hr}

...... ( 1)

{L}/{S-6}={8.4}/{60 × 60} \ { km} \/ {hr}

.....(2)
Divide eqution (1) by (2),

{S-6}/{S-4.5}={60 \×60 \×8}/{60 \×60 × 8.4}

(S-6) 8.4=(S-4.5) 8

0.4 S=14.4

S=36 \ { km} \/ {hr}

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