What is the length of the train ?
I. The train crosses a signal post in 9 seconds.
II. If the train with speed x kmph crosses another train 100m long coming from the opposite direction at 60 kmph in 15 seconds.

Options

A. if the data in statement I alone are sufficient to answer the questin, while the data in statement II alone are not sufficient to answer the question.
B. if the data in statement II alon are sufficient to answer the question, while the data in statement I alone are not sufficient to answer the question.
C. if the data either in statement I alone or in statement II alone in sufficient to answer the question.
D. if the data in both the statements I and II together are necessary to answer the question.

Explanation

From both the statements,
If the length of the train by y meter,
Speed of train `=y/9m//sec=y/9xx18/5=(2y)/(5)kmph`
Again, `((5y)/(9xx18)+60)==(15)/(60xx60)=(y+100)/(1000)`
`implies((5y)/(9xx10)+60)xx15/36=(y+100)/(10)" "...(i)`
It is to be noted that when a train crosses a pole, the distance covered = length of the train, When it crosses another train,
Relative speed `xx` time = sum of lengths of both trains. Hence, from equation (i), we can determine length or train. Length is (-ve) neglect that sign.