A submarine completed a 450 km training with an average speed of 50 km/h. For the first 180 km, it travelled at an average speed of 60 km/h.

Question

A submarine completed a 450 km training with an average speed of 50 km/h. For the first 180 km, it travelled at an average speed of 60 km/h. What was the average speed for the remaining distance? Km/h

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Ngọc Khuê 5 years 2021-08-03T05:15:29+00:00 1 Answers 291 views 0

Answers ( )

  1. thienthi
    1
    2021-08-03T05:16:47+00:00
    Reply

    Answer:

    45km/hr

    Explanation:

    Total distance=450km

    Total speed=50km/hr

    Total time= distance/speed

    =450/50

    =9hrs

    distance a=180km

    speed a=60km/hr

    Time a=180/60

    =3hrs

    Distance b=450-180=270km

    Speed b=?

    Time b=270/speed b

    Total time=time a + time b

    9=3+(270/speed b)

    270/speed b =9-3

    270/speed b =6

    6*speed b =270

    Speed b=270/6

    Speed b=45km/hr

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