DAA Distance, Speed, and Time Problems 3

Question 1

A car travels the first half of a journey at 60 km/h and the second half at 90 km/h. What is the average speed for the entire journey?

Accepted Answer

72 km/h

Answer

Average speed = 2 × 60 × 90 ÷ (60 + 90) = 10800 ÷ 150 = 72 km/h.

Question 2

A man rows downstream at 12 km/h and upstream at 6 km/h. What is the speed of the current?

Accepted Answer

3 km/h

Answer

Current speed = (downstream − upstream) ÷ 2 = (12 − 6) ÷ 2 = 3 km/h.

Question 3

A person travels 40 km in 4 hours on day one and 60 km in 6 hours on day two. What is the average speed over both days combined?

Accepted Answer

10 km/h

Answer

Total distance = 100 km; total time = 10 hours; average speed = 100 ÷ 10 = 10 km/h.

Question 4

Two cyclists start from opposite ends of a 120 km road at the same time. Cyclist A rides at 20 km/h and Cyclist B at 25 km/h. After how long will they meet?

Accepted Answer

2 hours 40 minutes

Answer

Combined speed = 45 km/h; time = 120 ÷ 45 = 8/3 hours = 2 hours 40 minutes.

Question 5

A boat's speed in still water is 15 km/h and the river current flows at 3 km/h. How long will it take the boat to travel 108 km downstream?

Accepted Answer

6 hours

Answer

Downstream speed = 15 + 3 = 18 km/h; time = 108 ÷ 18 = 6 hours.

DAA - Defence Aptitude Assessment Practice Test

DAA - Defence Aptitude Assessment Practice Test

DAA Distance, Speed, and Time Problems 3