**Question 46.**A car travels at a speed of 60 kmph for the first 2 hours, 50 kmph for the next 3 hours, and 70 kmph for the remaining distance. If the total distance covered is 320 km, how long does the car take to complete the journey?

- (a)6.12 hours
- (b)7.55 hours
- (c)4.10 hours
- (d) 5.71 hours

**Question 47.**A boat can travel a certain distance downstream in 6 hours. If it covers the same distance upstream in 12 hours, what is the speed of the boat in still water and the speed of the stream?

- (a) 10 kmph and 3 kmph.
- (b) 9 kmph and 4 kmph.
- (c) 8 kmph and 5 kmph.
- (d) 12 kmph and 2 kmph.

The speed of the boat downstream is x+y kmph and the speed of the boat upstream is x−y kmph.

The boat travels a certain distance downstream in 6 hours. This means that the distance traveled is 6(x+y) km.

The boat travels the same distance upstream in 12 hours. This means that the distance traveled is 12(x−y) km.

Since the boat travels the same distance downstream and upstream, we have 6(x+y)=12(x−y).

Solving for x, we get x=12 kmph.

Solving for y, we get y=2 kmph.