Question
A train passes by a lamp post at platform in 7 sec. and passes by the platform completely in 28 sec. If the length of the platform is 390m, then length of the train (in meters) is?
Answer: Option B
Length of train
$$ = \frac{{{\text{Length}}\,{\text{of}}\,{\text{the}}\,{\text{platform}}}}{{{\text{Difference}}\,{\text{in time}}}}$$ × (Time taken to cross a lamp post)
$$\eqalign{
& = \frac{{390}}{{28 - 7}} \times 7 \cr
& = \frac{{390}}{{21}} \times 7 \cr
& = \frac{{390}}{3} \cr
& = 130\,{\text{m}} \cr} $$
Was this answer helpful ?
Length of train
$$ = \frac{{{\text{Length}}\,{\text{of}}\,{\text{the}}\,{\text{platform}}}}{{{\text{Difference}}\,{\text{in time}}}}$$ × (Time taken to cross a lamp post)
$$\eqalign{
& = \frac{{390}}{{28 - 7}} \times 7 \cr
& = \frac{{390}}{{21}} \times 7 \cr
& = \frac{{390}}{3} \cr
& = 130\,{\text{m}} \cr} $$
Was this answer helpful ?
More Questions on This Topic :
Latest Videos
Latest Test Papers
Submit Solution