3159.A person crosses a 600 m long street in 5 minutes. What is his speed in km per hour?
3.6
7.2
8.4
10
Explanation:
| Speed =$ \left(\dfrac{600}{5 \times 60} \right) $m/sec. |
= 2 m/sec.
Converting m/sec to km/hr => m/sec =$\left(x \times\dfrac{18}{5}\right)$
| =$ \left(2 \times\dfrac{18}{5} \right) $km/hr |
= 7.2 km/hr.
3160.A and B walk around a circular track. A and B walk at a speed of 2 rounds per hour and 3 rounds per hour respectively. If they start at 8 a.m. from the same point in opposite directions, how many times shall they cross each other before 9.30 a.m.?
5
6
7
8
Explanation:
Relative speed = Speed of A + Speed of B [they walk in opposite directions]
= 2 + 3 = 5 rounds per hour
=> They cross each other 5 times in 1 hour and 2 times in 1/2 hour
Time duration from 8 am to 9.30 am = 1.5 hour
Hence they cross each other 7 times before 9.30 am
3161.Two boys starts from the same place walking at the rate of 5 kmph and 5.5 kmph respectively in the same direction. What time will they take to be 8.5 km apart?
17 hr
14 hr
12 hr
19 hr
Explanation:
Relative speed = 5.5 - 5 = 0.5 kmph [because they walk in the same direction]
distance = 8.5 km
time =$\dfrac{distance}{speed} = \dfrac{8.5}{0.5}$ = 17hr
3163.Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour?
9
10
12
20
Explanation:
Due to stoppages, it covers 9 km less.
| Time taken to cover 9 km =$ \left(\dfrac{9}{54} \times 60\right) $min= 10 min. |
3165.An athlete runs 200 metres race in 24 seconds. What is his speed?
20 km/hr
25 km/hr
27.5 km/hr
30 km/hr
Explanation:
Speed = $\dfrac{Distance}{Time} = \dfrac{200}{24}m/s = \dfrac{200}{24}\times \dfrac{18}{5}$km/hr
= $\dfrac{40 \times 3}{4}km/hr = 10 \times 3$km/hr = 30km/hr
44316.A man travelled a distance of 61 km in 9 hours. He travelled partly on foot at 4 km/hr and partly on bicycle at 9 km/hr.
What is the distance travelled on foot?
What is the distance travelled on foot?
12 km
14 km
16 km
18 km
Explanation:
Let the time in which he travelled on foot = x hr
Then the time in which he travelled on bicycle = (9−x) hr
distance = speed $ \times$ time
=> 4x + 9(9 − x) = 61
=> 4x + 81− 9x = 61
=> 5x = 20
=> x = 4
Distance travelled on foot = 4x = 4 $ \times$ 4 = 16 km
Let the time in which he travelled on foot = x hr
Then the time in which he travelled on bicycle = (9−x) hr
distance = speed $ \times$ time
=> 4x + 9(9 − x) = 61
=> 4x + 81− 9x = 61
=> 5x = 20
=> x = 4
Distance travelled on foot = 4x = 4 $ \times$ 4 = 16 km
44318.A motor cyclist covers a distance of 20 km at a speed of 10km per hour. Calculate the time taken to cover this distance.
2 hours
4 hours
5 hours
6 hours
Explanation:
Solution: Speed = 10 km/hour
Distance covered = 20 km
Time = distance/speed
= 20/10 hour
= 2 hours
Solution: Speed = 10 km/hour
Distance covered = 20 km
Time = distance/speed
= 20/10 hour
= 2 hours
44319.A man goes to his office from his house at a speed of 3 km/hr and returns at a speed of 2 km/hr.
If he takes 5 hours in going and coming, what is the distance between his house and office?
If he takes 5 hours in going and coming, what is the distance between his house and office?
3 km
4 km
5 km
6 km
Explanation:
Speed of House to Office is = 3 km/hr.
Speed of Office to House is = 2 km/hr.
Ratio of his speed = 3 : 2
Therefore, ratio of the time taken = 2 : 3
Since total time taken is 5 hours, he has taken 2 hours to travel to his office and 3 hours to come back.
Distance between his house and office
= 2 $ \times$ 3 = 6 km
Speed of House to Office is = 3 km/hr.
Speed of Office to House is = 2 km/hr.
Ratio of his speed = 3 : 2
Therefore, ratio of the time taken = 2 : 3
Since total time taken is 5 hours, he has taken 2 hours to travel to his office and 3 hours to come back.
Distance between his house and office
= 2 $ \times$ 3 = 6 km
44320.A man complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr
and second half at the rate of 24 km/hr. Find the total journey in km.
and second half at the rate of 24 km/hr. Find the total journey in km.
121 km
242 km
224 km
112 km
Explanation:
Average Speed = $ \dfrac{2 \times 21 \times 24}{21+24}$ = 22.4 km/hr
Total distance = 22.4 $\times $ 10 = 224 km
Average Speed = $ \dfrac{2 \times 21 \times 24}{21+24}$ = 22.4 km/hr
Total distance = 22.4 $\times $ 10 = 224 km