Quantitative Aptitude Set -472
Jan 16 2025
Here we are providing new series of Quantitative Aptitude Questions for upcoming exams, so the aspirants can practice it on a daily basis.
1) The boat can cover 120 km against the stream in 8 hours and the same boat cover 150 km along the stream in 6 hours. What is the ratio of the speed of boat in
A.3:2
B.8:7
C.4:1
D.5:3
E.None of these
2) The ratio of the speed of boat in still water to the speed of the stream is 5:4. If the boat covers 72 km distance in upstream and downstream in 20 hours, then find the speed of boat in still water?
A.20 kmph
B.16 kmph
C.24 kmph
D.25 kmph
E.None of these
3) The speed of the current is 4 km/hr. A boat goes 10 km upstream and comes back to starting point in 80 min. What is the speed of the boat in still water? (In km/hr)
A.10
B.16
C.14
D.12
E.8
4) A man takes to row 120 km along the stream is one-third of the time taken to row against the stream. Find the speed of the boat in still water, if the speed of stream is 10 km/hr?
A.24 km/hr
B.20 km/hr
C.18 km/hr
D.14 km/hr
E.None of these
5) The boat will take 2 hours to cover the distance of 20km in downstream and while covering the same distance in upstream it will take 5 hours. Find the speed of the current.
A.2kmph
B.3kmph
C.4kmph
D.5kmph
E.None of these
Answers :
1) Answer: C
Downstream speed = 150/6 = 25 kmph
Upstream speed = 120/8 = 15 kmph
Speed of the boat in still water = 1/2(downstream speed + upstream speed)
=> 1/2(25 + 15) = 20 kmph
Speed of stream=1/2 (downstream speed – upstream speed)
=> 1/2 (25 – 15)
=> 5 kmph
Required ratio = 20:5
= 4:1
2) Answer: A
Downstream speed=5x + 4x=9x
Upstream speed=5x – 4x=x
According to the question,
72/9x + 72/x=20
After solving this we have,
x=4 kmph
Speed of the boat in still water=5 * 4=20 kmph
3) Answer: B
Let the speed of boat be x km/hr
According to the question, 10/(x – 4) + 10/(x + 4) = 80/60
=> 10 (x + 4 + x – 4) = 4/3(x2 – 16)
=> 15x = x2 – 16
=>x2 – 16 – 15x = 0
=> x = 16, -1 (taking only +ive value for real time events)
Therefore, the speed of boat in still water = 16km/hr
4) Answer: B
Let us take the speed of the boat in still water be x km/hr,
120/(x + 10) = (1/3)*(120/(x - 10))
x + 10 = 3x - 30
2x = 40
x = 20
Speed of the boat in still water = 20 km/hr
5) Answer: B
Downstream speed=20/2=10kmph
Upstream speed=20/5=4kmph
Speed of the current=1/2*(10-4)=3kmph
