Speed, Time and Distance
 Two donkeys are standing 400 metres apart. First donkey can run at a speed of 3 m/sec and the second can run at 2 m/sec. If two donkeys run towards each other after how much time (in seconds) will they bump into each other?

 60
 80
 400
 40

View Hint View Answer Discuss in Forum
Distance between both donkeys = 400 metre.
Relative speed = (3 + 2) m./sec. = 5 m./sec.∴ Required time = Distance Relative speed = 400 = 80 seconds 5 Correct Option: B
Distance between both donkeys = 400 metre.
Relative speed = (3 + 2) m./sec. = 5 m./sec.∴ Required time = Distance Relative speed = 400 = 80 seconds 5
 A man travels for 14 hours 40 minutes. He covers half of the journey by train at the rate of 60 km/hr and rest half by road at the rate of 50 km/hr. The distance travelled by him is :

 720 km
 800 km
 960 km
 1000 km

View Hint View Answer Discuss in Forum
Let total distance covered be 2x km.
Total time = 14 hours 40 minutes= 14 40 hours = 14 2 hours 60 3 = 44 hours 3 Time = Distance Speed
According to the question,x + x = 44 60 50 3 ∴ 5x + 6x = 44 300 3 ⇒ 11x = 44 300 3 ⇒ x = 44 × 300 = 400 3 11
∴ Total distance
= 2x = 2 × 400 = 800 kmCorrect Option: B
Let total distance covered be 2x km.
Total time = 14 hours 40 minutes= 14 40 hours = 14 2 hours 60 3 = 44 hours 3 Time = Distance Speed
According to the question,x + x = 44 60 50 3 ∴ 5x + 6x = 44 300 3 ⇒ 11x = 44 300 3 ⇒ x = 44 × 300 = 400 3 11
∴ Total distance
= 2x = 2 × 400 = 800 km
 Sound travels 330 metre in a second.When the sound follows the flash of lightning after 10 seconds the thunder cloud will be at a distance of :

 1300 metre
 2000 metre
 3650 metre
 3300 metre

View Hint View Answer Discuss in Forum
Distance = Speed × Time
= 330 × 10 = 3300 metreCorrect Option: D
Distance = Speed × Time
= 330 × 10 = 3300 metre
 A man travelled a distance of 61 km. in 9 hours, partly by walking at the speed of 4 km./hr. and partly on bicycle at the speed of 9 km./hr. The distance covered by walking is

 16 km.
 12 km.
 15 km.
 17 km.

View Hint View Answer Discuss in Forum
Let the distance covered on foot be x km.
∴ Distance covered on cycle = (61 – x) km.Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ x − x = 9 − 61 4 9 9 ⇒ 9x − 4x = 81 − 61 36 9 ⇒ 5x = 20 36 9 ⇒ x = 20 × 36 = 16 km. 9 5 Correct Option: A
Let the distance covered on foot be x km.
∴ Distance covered on cycle = (61 – x) km.Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ x − x = 9 − 61 4 9 9 ⇒ 9x − 4x = 81 − 61 36 9 ⇒ 5x = 20 36 9 ⇒ x = 20 × 36 = 16 km. 9 5
 A farmer travelled a distance of 61 km in 9 hours. He travelled partly on foot at a speed of 4 km/hour and partly on bicycle at a speed of 9 km/hour. The distance travelled on foot is :

 14 km.
 16 km.
 20 km.
 18 km.

View Hint View Answer Discuss in Forum
Length of journey on foot = x km. (let).
∴ Length of journey on cycle = (61 – x ) km.
According to the question,Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ 9x + 244 − 4x = 9 36
⇒ 5x + 244 = 36 × 9 = 324
⇒ 5x = 324 – 244 = 80⇒ x = 80 = 16 km 5 Correct Option: B
Length of journey on foot = x km. (let).
∴ Length of journey on cycle = (61 – x ) km.
According to the question,Time = Distance Speed ∴ x + 61 − x = 9 4 9 ⇒ 9x + 244 − 4x = 9 36
⇒ 5x + 244 = 36 × 9 = 324
⇒ 5x = 324 – 244 = 80⇒ x = 80 = 16 km 5