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Question 36: A boat goes 50 km upstream in 10 hours and a distance of 40 km downstream in 8 hours. The speed of the boat in still water is [1] 0 kmph [2] 10 kmph [3] 7.2 kmph [4] 5 kmph

Answer:

Option: 4

Explanation:

Speed upstream = 50/10 = 5 kmph.

Speed downstream = 40/8 = 5 kmph.

Since both these speeds are equal, it means that the water is still.

=>Required answer = 5 kmph

Two cyclists start from the same place to ride in the same direction. A starts at noon at 8 kmph while B starts at 2 pm at the rate of 10 kmph.

Question 37: How far will A have ridden before he is overtaken by B? [1] 76 km [2] 80 km [3] 84 km [4] 75 km

Answer:

Option: 2

Explanation:

By the time B starts, A has already covered 16 km.

Difference between B's speed and A's speed is 2 km/hr.

So, total time for B to catch up with A will be \(\frac{{16}}{2}\) i.e.. 8 hrs.

:. At 10 pm, B will overtake A.

Distance covered by A before he is overtaken by B = 10 x 8 = 80 km.

i.e. A and B will be 5 km apart at \(\frac{{11}}{2}\) hrs after A's start and \(\frac{{21}}{2}\) hrs after B's start, i.e. at 7.30 pm and 12.30 am next day.

Hence required answers are 80 km, 7.30 pm and 12.30 am next day.

Question 38: At what times A and B will be 5 km apart? [1] 7.30 pm on the same day and 1.30 am on the next day. [2] 7.30 pm on the same day and 12.30 am on the next day. [3] 8.30 pm on the same day and 1.30 am on the next day. [4] 8.30 pm on the same day and 12.30 am on the next day.

Answer:

Option: 2

Explanation:

By the time B starts, A has already covered 16 km.

Difference between B's speed and A's speed is 2 km/hr.

So, total time for B to catch up with A will be \(\frac{{16}}{2}\) i.e.. 8 hrs.

:. At 10 pm, B will overtake A.

Distance covered by A before he is overtaken by B = 10 x 8 = 80 km.

i.e. A and B will be 5 km apart at \(\frac{{11}}{2}\) hrs after A's start and \(\frac{{21}}{2}\) hrs after B's start, i.e. at 7.30 pm and 12.30 am next day.

Hence required answers are 80 km, 7.30 pm and 12.30 am next day.

Question 39: A train runs at 45 kmph. How far does it go in 6 seconds? [1] 45 m [2] 60 m [3] 75 m [4] 55 m

Answer:

Option: 3

Explanation:

\(45 \times \frac{5}{{18}} \times 6 = 75m\)

Question 40: If the speed of train is 92.4 kmph, then how many metres does it cover in 20 minutes? [1] 30800 m [2] 32800 m [3] 38200 m [4] 35500 m