A 300 metre long train crosses a platform in 39 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform?

1320 m
2350 m
3650 m
4Data inadequate

Answer:- 1

Explanation:-

Solution:

\begin{aligned} Speed = (\frac{300}{18}) m/sec \\ = \frac{50}{3} m/sec \\ Let the length of the platform be x metres . \\ Then, (\frac{x + 300}{39}) = \frac{50}{3} \\ \Rightarrow 3 (x + 300) = 1950 \\ \Rightarrow x = 350 m . \end{aligned}

$\eqalign{ & {\text{Speed}} = \left( {\frac{{300}}{{18}}} \right)\,{\text{m/sec}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{50}}{3}\,{\text{m/sec}} \cr & {\text{Let}}\,{\text{the}}\,{\text{length}}\,{\text{of}}\,{\text{the}}\,{\text{platform}}\,{\text{be}}\,x\,{\text{metres}}{\text{.}} \cr & {\text{Then}},\left( {\frac{{x + 300}}{{39}}} \right) = \frac{{50}}{3} \cr & \Rightarrow 3\left( {x + 300} \right) = 1950 \cr & \Rightarrow x = 350\,m. \cr}$