IBPS SO Prelims Exam Model Paper 10

Given
Speed of boat in downstream =

20‌km

h

Total time =8 hours
Formula
Distance = Speed × Time
Downstream speed = speed of boat in still water + speed of stream
Upstream speed = speed of boat in still water − speed of stream
Calculation
Let speed of boat and speed of stream be x and y respectively
⇒x+y=20
Now,x= 4y‌
⇒4y+y=20
⇒y=4‌kmph
⇒x=4×4=16‌kmph
Upstream‌speed=16−4=12‌kmph
Let,total‌distance‌be‌d
According‌to‌question,

d

(2×20)

+

d

(2×12)

=8
⇒

d

40

+

d

24

=8
⇒3d+5d=8×120
⇒8d=960
⇒d=120
∴ Total distance =120 km