7
Q:
A) 4.5 km/h and 3 km/h | B) 4.5 km/h and 0.5 km/h |
C) 4 km/h and 2 km/h 5 km/h and 2 km/h | D) 5 km/h and 2 km/h |
Answer: B) 4.5 km/h and 0.5 km/h
Explanation:
Explanation:
Distance travelled by boat in upstream=24km
Time taken = 6 h
Speed of the boat in upstream = 24/6 = 4 km/h
And distance travelled by boat in downstream = 20 km
Time taken = 4h Speed of the boat in downstream = 20/4 km/h = 5 km/h
Now, speed of the boat in still water = 1/2 [ speed of the boat in upstream + speed of the boat in downstream] =1/2 [4 + 5] = 1/2 × 9 = 4.5 km/h
And speed of the current = 1⁄2 [speed of the boat in downstream – speed of the boat in upstream] = 1/2 [5 – 4] = 1/2 × 1 = 0.5 km/h