Speed, Time and Distance

reaches school 20 minutes earlier. Find his usual time.By walking 5 of usual speed a student 3

 45 minutes
 50 minutes
 60 minutes
 None of these

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5/3 of usual speed means 3/5 of usual time as he reaches earlier.
∴ 3 usual time + 20 minutes = Usual time 5 20 minutes = 1 − 3 usual time 5 = 2 usual time 5 ∴ Usual time = 20 × 5 = 50 minutes. 2 Correct Option: B
5/3 of usual speed means 3/5 of usual time as he reaches earlier.
∴ 3 usual time + 20 minutes = Usual time 5 20 minutes = 1 − 3 usual time 5 = 2 usual time 5 ∴ Usual time = 20 × 5 = 50 minutes. 2

is marked on my cards by 10 minutes. Find my usual time.Walking 3 of my usual speed, a late 4

 30 minutes
 35 minutes
 32 minutes
 36 minutes

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Since I walk at 3/4 of my usual speed the time taken is 4/3 of my usual time.
[∵ the speed and time are in the inverse ratio]∴ 4 of usual time 3
= Usual time + Time I reach late∴ 1 of usual time 3
= 10 minutes
∴ Usual time
= 10 × 3 = 30 minutes.Correct Option: A
Since I walk at 3/4 of my usual speed the time taken is 4/3 of my usual time.
[∵ the speed and time are in the inverse ratio]∴ 4 of usual time 3
= Usual time + Time I reach late∴ 1 of usual time 3
= 10 minutes
∴ Usual time
= 10 × 3 = 30 minutes.
 A man has to reach a place 40 kms away. He walks at the rate of 4 km per hr. for the first 16 kms and then he hires a rickshaw for the rest of the journey. However if he had travelled by the rickshaw for the first 16 kms and the remaining distance on foot at 4 km per hr, he would have taken an hour longer to complete the journey. Find the speed of rickshaw.

 6.5 kmph
 7.5 kmph
 6 kmph
 8 kmph

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Let the speed of Rickshaw be 'x ' .
Then, time taken to cover 16 km on foot and 24 km on Rikshaw= 16 + 24 hrs 4 x
and time taken to travel 24 km on foot & 16 km on Rikshaw= 16 + 24 hrs x 4
According to question,= 16 + 24 + 1 = 16 + 24 4 x x 4 ⇒ 5 + 24 = 16 + 6 x x ⇒ 24 − 16 = 1 x
⇒ x = 8 km/hrCorrect Option: D
Let the speed of Rickshaw be 'x ' .
Then, time taken to cover 16 km on foot and 24 km on Rikshaw= 16 + 24 hrs 4 x
and time taken to travel 24 km on foot & 16 km on Rikshaw= 16 + 24 hrs x 4
According to question,= 16 + 24 + 1 = 16 + 24 4 x x 4 ⇒ 5 + 24 = 16 + 6 x x ⇒ 24 − 16 = 1 x
⇒ x = 8 km/hr
 If a boy walks from his house to school at the rate of 4 km per hr, he reaches the school 10 minutes earlier than the scheduled time. However if he walks at the rate of 3 km per hr, he reaches 10 minutes late. Find the distance of his school from his house.

 3.5 km
 3 km
 4 km
 4.5 km

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Let the distance be x kms.
∴ Time taken at 4 km per hr. t_{1}= x hrs. 4
Time taken at 3 km per hr.t_{2}= x hrs. 3
Difference in timings
= 10 + 10 = 20 minutesor 20 = 1 hour 60 3 ∴ x − x = 1 3 4 3 ⇒ 4x − 3x = 1 12 3 ⇒ x = 1 12 3
∴ x = 4 km.
Hence the required distance
= 4 kms.Correct Option: C
Let the distance be x kms.
∴ Time taken at 4 km per hr. t_{1}= x hrs. 4
Time taken at 3 km per hr.t_{2}= x hrs. 3
Difference in timings
= 10 + 10 = 20 minutesor 20 = 1 hour 60 3 ∴ x − x = 1 3 4 3 ⇒ 4x − 3x = 1 12 3 ⇒ x = 1 12 3
∴ x = 4 km.
Hence the required distance
= 4 kms.
 A car can finish a certain journey in 10 hours at a speed of 48 km per hr. In order to cover the same distance in 8 hours, how much the speed be increased by ?

 10 kmph
 12 kmph
 14 kmph
 15 kmph

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Time = 10 hours,
Speed = 48 km per hr.
∴ Distance = Speed × Time
= 48 × 10 = 480 km
Now, this distance of 480 kms is to be covered in 8 hours.
Hence, the required Speed= Distance = 480 New time 8
= 60 km per hr.
∴ Increase in speed
= 60 – 48 = 12 km per hr.Correct Option: B
Time = 10 hours,
Speed = 48 km per hr.
∴ Distance = Speed × Time
= 48 × 10 = 480 km
Now, this distance of 480 kms is to be covered in 8 hours.
Hence, the required Speed= Distance = 480 New time 8
= 60 km per hr.
∴ Increase in speed
= 60 – 48 = 12 km per hr.