# 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.

1
by shailaahmed

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

### This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.

-----------------------------------------------------------------------------------
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

---------------------------------------------------------------------------------
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

------------------------------------------------------------------------------------
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