Data Sufficiency Question 58
- Find the speed of train.
I. The train crosses a 120 metre long platform in 10 seconds and a vertical pole in 6 seconds while travelling at the same speed.
II. The train 180 metre long passes a person running at the speed of $1.2 m / sec$ in the same direction in which the train is running in 6.25 seconds.
Show Answer
Correct Answer: 58. (3)
Solution: 58. (3) From statement I,
Let the length of train be $x$ metre.
$\therefore$ Speed of train
$=\frac{x+120}{10}=\frac{x}{6}$
$\Rightarrow \frac{x+120}{5}=\frac{x}{3}$
$\Rightarrow 5 x=3 x+360$
$\Rightarrow 2 x=360 \Rightarrow x=\frac{360}{2}$ $=180$ metre
$\therefore$ Speed of train $=\frac{x}{6}=\frac{180}{6}$
$=30 \mathrm{~m} / \mathrm{sec}$.
From statement II,
Let the speed of train be $x \mathrm{~m}$./ sec.
$\therefore \frac{180}{x-1.2}=6.25$
$\Rightarrow 6.25 x-6.25 \times 1.2=180$
$\Rightarrow 6.25 x=180+7.5=187.5$
$\Rightarrow x=\frac{187.5}{6.25}=30 \mathrm{~m} / \mathrm{sec}$.
BETA
