24. A cab driver covers a distance between A and B at a speed of 40 km/h and on the return his speed is 60 km/h. He goes again from A to B at thrice the original speed that of from A to B. Now, he starts from B to C with the average speed of the journey till now, with its speed increasing every hour by 5 km/h. After how many hours his speed will reach 100 km/h??
8 hours
4 hours
12 hours
9 hours
Answers
Solution :-
Let us assume that, the distance from A to B is 120 km.
so,
→ Time taken from A to B = Distance/speed = 120/40 = 3 hours.
→ Time taken from B to A = D/S = 120/60 = 2 hours.
again,
→ Time taken from A to B = D/(3 * speed from A to B) = 120/(3 * 40) = 120/120 = 1 hour.
then,
→ Average speed till now = (Total distance covered)/(Total time taken) = (120 + 120 + 120) / (3 + 2 + 1) = 360/6 = 60 km/h .
Now,
→ speed from B to C in first hour = 60 km/h .
→ speed in second hour = 65 km/h .
A/q,
→ a + (n - 1)d = an
→ 60 + (n - 1)5 = 100
→ 60 + 5n - 5 = 100
→ 55 + 5n = 100
→ 5n = 100 - 55
→ 5n = 45
→ n = 9 hours. (Ans.)
Hence, After 9 hours his speed will reach 100 km/h.
Learn more :-
A leak in the body of a ship which can admit 5 units of water in 16 minutes got detected when it is 40km
away from the s...
https://brainly.in/question/26688438
A train starting from a station X was to arrive at a station Y at 6:06 PM. It could travel at 62.5% of its usual
speed a...
https://brainly.in/question/26746228