Multiple choice

Find the length of the train P? Statement I – The train P cross the train Q in 6 sec when train Q is not moving. Train Q cross train R in 68 sec when both are moving same direction, speed of train R is 25m/sec. Statement II – Train P cross train R in 64 sec when both are moving same direction. Length of train Q is 140m

  1. Only Statement I alone.

  2. Only Statement II alone.

  3. Both Statements I and II together.

  4. Neither Statement I nor II is sufficient.

  5. Either Statement I or II.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statement I gives info about P crossing Q and Q crossing R, but no info on P's length. Statement II gives P crossing R and Q's length. We need speeds and lengths of P, Q, and R. We have too many variables and not enough equations to isolate the length of P.

AI explanation

Let the lengths of trains P, Q, and R be p, q, and r, with speeds S_p, S_q, and S_r. From Statement I, train Q crossing train R in 68 seconds means (q + r) equals 68 times (S_q minus 25), but without knowing q, r, or S_q, we cannot find p. Statement II gives the equation (p + r) equals 64 times (S_p minus 25) when P crosses R, but this single equation contains three unknowns. Combining both statements still only leaves you with an incomplete system of equations, as it lacks the values for the speed or length of train R. Therefore, neither statement alone nor together provides enough data to determine the length of train P.

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