Practice NAT questions with answers and explanations.
Choose an option to check your answer.
Downstream speed equals still-water speed plus stream speed.
Thus, 12 + 3 = 15 km/h.
Choose an option to check your answer.
If 40% takes 12 days, 10% takes 3 days.
The remaining 60% takes 18 days.
Choose an option to check your answer.
Upstream speed equals still-water speed minus stream speed.
Thus, 10 - 2 = 8 km/h.
Choose an option to check your answer.
The leak rate is 1/9 - 1/12 = 1/36 tank per hour.
Thus, the leak alone empties the tank in 36 hours.
Choose an option to check your answer.
Downstream speed is 15 km/h and upstream speed is 10 km/h.
Still-water speed is their average: 12.5 km/h.
Choose an option to check your answer.
Speed equals distance divided by time.
Thus, 180 ÷ 3 = 60 km/h.
Choose an option to check your answer.
Distance equals speed multiplied by time.
Thus, 72 × 2.5 = 180 km.
Choose an option to check your answer.
Their combined rate is 1/8 + 1/12 = 5/24 tank per hour.
Time is 24/5 = 4.8 hours.
Choose an option to check your answer.
The net rate is 1/10 - 1/15 = 1/30 tank per hour.
Therefore, the tank fills in 30 hours.
Choose an option to check your answer.
The net hourly rate is 1/4 - 1/12.
This equals 2/12 = 1/6.
Choose an option to check your answer.
Three taps together have three times the rate of one tap.
One tap therefore takes 3 × 6 = 18 hours.
Choose an option to check your answer.
The remaining part is 3/4 of the tank.
At 8 hours per full tank, 3/4 takes 6 hours.
