Very urgent friends please help me i have to submit it by tomorrow itself Topic: Speed , Time And DistanceQuestion 1: express in meter/second: 108 km/hrQuestion 2: express in km/hr: 15.5 m/s Question 3: A Train Passes Through A Tunnel Whose Length Is 525 m , In 31 1/4 Seconds Moving At A Speed Of 72 km/hr . Find The Length Of The Train. Question 4: Running At 4/3 Of His Usual Speed, A Person Improves His Timings By 10 Minutes. Find His Usual Time To Cover The Distance. Question 5: A Scooterist Covered A Distance In 10 Hours. He Covered The First Half Of The Distance At Speed Of 21 km/hr And The Other Half At A Speed Of 24 km/hr. Find The Distance He Travelled.

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by shailaahmed

2015-01-28T20:23:21+05:30

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speed = 72 km/h = 72×(5/18) m/s = 20 m/s
time = 31 1/4 second = 31.25 seconds
distance covered = speed × time = 20 × 31.25 = 625m
length of tunnel = 525m
length of train = distance covered - tunnel length = 625 - 525 = 100m

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let the usual time taken to cover the distance = t minutes
If the speed increase by n times, the the time taken decreases by n times as they are inversely proportional.
so if speed becomes 4/3 times of usual, time taken will be 3/4 times of usual i.e. 3t/4. So
t - 3t/4 = 10
⇒ t/4 = 10
⇒ t = 4*10 = 40 minutes

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the speeds are 21 km/h and 24 km/h. Since he covered equal distance,

average speed =  km/h
time = 10 hours
distance = 22.4*10 = 224 km