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Distance travelled at 20 km/h = 20×1.5 = 30 km
Distance travelled at 4 km/h = 4×y = 4y km
We know that,
Average speed = Total distance/Total time
∴ 10 = [34 + 30 + 4y]/[4 + 1.5 + y]
⇒10 = [64 + 4y]/[5.5 + y]
⇒ 10[5.5 + y] = [64 + 4y]
⇒55 + 10y = 64 + 4y
⇒6y = 9
⇒ y = 9/6 = 1.5
Hence, option C is the correct answer.
Speed of first train = 70 km/h
Speed of another train = 34 km/h
Time to cross = 25 seconds
Relative speed = 70 – 34 = 36 km/h × 5/18 = 10 m/s (running in same direction)
Distance travelled = Length of both trains = 25 × 10 = 250 metres
Hence, option B is the correct answer.
= 120/80 = 1.5 hr
Time taken to travel 100 km at 40 km/h
= 100/40 = 2.5 hr
Average speed of 220 km distance = Total distance/Total time
= 220/[1.5 + 2.5] = 55 km/hr
He comes back to the starting point at the speed of 75 km/hr.
∴ Average speed of whole journey = [2 × 55 × 75]/[55 + 75]
= 63.46 km/h
Hence, option A is the correct answer.
∴ Relative speed = 24 – 18 = 6 km/hr
= 6 × 5/18 = 5/3 m/s
Required time = 200/(5/3)
= 120 sec
Given, Distance = 4800 m = 4.8 km
Time = 18 minutes = hrs
Speed = = 16 km/h
Hence, Option C is the correct answer.
S1 = 720 km/hr
S2 = 720/2 = 360 km/hr
S3 = 360/2 = 180 km/hr
S4 = 180/2 = 90 km/hr
Let the distance of each trip be d km.
∴ Total distance = 4d
= 4d/[d/720 + d/360 + d/180 + d/90]
= 4d/d[(1 + 2 + 4 + 8)/720]
= 4/[(15)/720]
= (4)(720)/15
= 192 km/h
Actual time to reach examination centre = 6 – 0.5 = 5.5 hours
3/5 of total distance = (3/5) × 250 = 150 km
Remaining distance = 250 – 150 = 100 km
Remaining time = 5.5 – 3.5 = 2 hours
Speed = Distance/time
= 100/2 = 50 km/h
Speed of first train = 80 km/h
Speed of second train = 120 km/h
Relative speed = 120 + 80 = 200 km/h
Distance between them 10 minutes before crossing = Speed × Time
= 200 × = = 33.33 km
In one hour faster train travel 95 – 80 = 15 km more distance.
Time taken by 180 km more distance = = 12 hours
Relative speed = 80 + 95 = 175 km/h
Distance between Bangalore and Chennai = 175 × 12 = 2100 km
Speed = 21 m/s =
In first 10 minutes distance travelled by car = = 12.6 km
Total distance = 12.6 + 9 + 10 = 31.6 km
Total time = 10 + 10 + 10 = 30 minutes = hours = 0.5 hours
Average speed =
= = 63.2 km/h
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