An engine approaches a hill with a constant speed. When it is at a distance of $0.9 km$ it blows a whistle, whose echo is heard by the driver after $5$ sec. If speed of sound in air is $330 m/s$, the speed of engine is .... $m/s$

107-157

  • A

    $10$

  • B

    $20 $

  • C

    $30$

  • D

    $40 $

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