Suppose length of the train = L m
Speed of the train = 60 km/h = 60 x 1000 = 60000 m/h
Length of tunnel = 1.5 km = 1500 m
Time taken by train = 2 min = 1/30 h
Time = Distance/Speed
? 1/30 = L + 1500/60000
? l = 500 m
Let the distance traveled on foot be x km
Then, distance converted by bicycle = (45 - x) km
? x/3 + (45 -x) /8 = 83/4 = 35/4
? (8x + 135 - 3x)/24 = 35/4
? 5x + 135 = 210
? 5x = 75
? x = 15
? Distance converted by bicycle = (45 - 15) = 300 km
Let distance between Manipur and Dispur = D km
Average speed of train from Manipur = D/4 km/h
Average speed of train from Dispur = 2D/7 km/h
Let they meet T h after 6:00 am.
Then, according to the question,
(D/4 x T) + 2D/7 x (T - 2) = D
? T/4 + 2(T - 2)/7 = 1
? 7T + 8(T - 2) = 28
? 15T = 44
? T = 44/15 h = 2h 56 min
Clearly, trains meet 2 h 56 min after 6:00 am.
It means the trains meet at 8:56 am.
Let they meet after x h.
Then, according to the question,
3x + 4x = 17.5
? 7x = 17.5
? x = 17.5 / 7 = 2.5 h
So, they meet 2.5 h after 8:00 am.
It means they meet at 10:30 am.
Time = Total distance / Relative speed
4.5/60 hr. = (450/1000) / x
? x = 6 km/h
Relative speed = Speed of car - Speed of man
6 = x - 6
? x = 12 km/h
(speed of wind) / (speed of car) = (Time utilised) / (time saved)
? 332/x = 332/28
? x = 28 m/s
Let the speed of the train during returning journey be x km/h
Speed during onward journey = x + 25x/100 = 5x/4 km/h.
Distance coverd in onward journey = 800 / 2 = 400 km
Total time taken = Covered distance / Speed
Time taken by train in onward journey = 400/(5x/4)
and time taken in returning journey = 400/x
Thus, 400/(5x/4) + 400/x = 16
? 320/x + 400/x = 16
? 16x = 720
? x = 45 km/h
Speed of the train in the onward journey = 5 x 45/4 = 56.25 km/h
Since, ratio of speeds of Meena and teena is 2 : 3.
? Ratio of time taken = 3 : 2
If, Teena takes x min to walk from A to B, then Meena takes (x + 20) min.
? (x + 20)/x = 3/2 ? 2x + 40 = 3x
? x = 40 min
Hence, Meena takes 60 min walking at her usual speed and at double the speed, she would take 30 min.
Relative speed of express train to local train = 65 - 29 = 36 km/h
= 36 x (5/18) m/s = 10 m/s
? Length of faster train = 10 x 16 = 160 m
Let total distance covered in the whole journey = L km
? 2L/25 + 21L/50 + 2 = L
? L = 4
? Total distance covered = 4 km
Number of gaps between 25 telephone posts = 24
Distance travelled in 1 min = 40 x 24 = 960 m
Speed = (960 x 60)/1000 = 57.6 km/h
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