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Bunuel
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Nidzo
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Scholar94
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Azeem123
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But the question says train Y speed is Y (it can be constant or variable) then how can we choose A?
Nidzo
As train X leaves \(1.5\) hours before train Y and travels at \(x\) mph, then train X will be \(1.5x\) miles ahead when Y begins its trip.

As Y is travelling at a faster speed of \(y\) mph, their relative speed will be \(y - x\).

This means that \(y\) will pass \(x\) after (formula for time = distance/speed): \(\frac{1.5x}{y-x}\)


­(1) y = 4x/3

Plugging this into \(\frac{1.5x}{y-x}\) gives:

\(\frac{1.5x}{\frac{4}{3}x-x}\)

\(\frac{1.5x}{\frac{1}{3}x}\)

\(4.5\) hours.

SUFFICIENT

(2) x = 60 miles per hour

Plugging this into \(\frac{1.5x}{y-x}\) gives:

\(\frac{90}{y-60}\)

As we know nothing about \(y\) we cannot solve the question with only this info.

INSUFFICIENT


ANSWER A
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Azeem123
But the question says train Y speed is Y (it can be constant or variable) then how can we choose A?

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Fixed that to mention that y is a constant speed.
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