Question

2
11. A boat goes 24 km upstream and 35 km downstream in
9 hour. It was goes 30 km upstream and 21 km
downstream in 8 hour. The speed of the boat in still
water is:
a) 8 b) 6 c) 12 d) 6.5

Answer 1

Step-by-step explanation:

Let speed of boat in still water be a km/hr.

Let rate of the current be b km/hr.

∴ Speed of the boat upstream =(a−b) km/hr.

∴

a−b

24

+

a+b

28

=6 ...(i)

and

a−b

30

+

a+b

21

=

2

13

..(ii)

From (i) and (ii), we have

a−b

1

=

6

1

and

a+b

1

=

14

1

⇒a−b=6 and a+b=14

⇒a=10 km/hr.