Mathematical Aptitude - Time and Distance
- Option : B
- Explanation : Due to stoppages, it covers 9 km less.
Time taken to cover 9 km = 9/54 × 60 min = 10 min
- Option : B
- Explanation : Average speed = (2 × 21 × 24)/(21 + 24) = 22.4 kmph
Distance = Time × Speed = 22.4 × 10 = 224
- Option : C
- Explanation : As the distance in both ways is same, we can apply
the formula 2xy/x + y.
Average speed = (2 × 64 × 80)/(64 + 80) = 71.11 kmph
- Option : C
- Explanation : Let the distance travelled in first phase be x km.
Then, distance travelled in second phase = (610 − x) km.
Hence, x/40 + (610 − x)/90 = 9 hours
⇒ x = 160 km
- Option : B
- Explanation : Distance to be travelled = 320 m
Speed = 36 kmph = 36 × 5/18 = 10 m/s
Time taken = D/S = 320/10 = 32 s
