Quantitative Aptitude and Reasoning Flashcards

A train 240 meters long passes a pole in 12 seconds. How long will it take to pass a platform 360 meters long?

Answer: 30 seconds

Speed = 240/12 = 20 m/s; total distance = 240+360 = 600 m; time = 600/20 = 30 seconds.

If 15 workers can complete a job in 8 days, how many days will 10 workers take to complete the same job?

Answer: 12 days

Total work = 15×8 = 120 worker-days; days for 10 workers = 120/10 = 12 days.

A number is increased by 20% and then decreased by 20%. The net change is:

Answer: 4% decrease

Net multiplier = 1.2 × 0.8 = 0.96, which is a 4% decrease from the original.

In a sequence 3, 6, 12, 24, 48, __, what is the next term?

Answer: 96

Each term is doubled, so 48 × 2 = 96.

The average of 5 consecutive odd numbers is 25. What is the largest of these numbers?

Answer: 29

The middle (3rd) number equals the average = 25, so consecutive odds are 21, 23, 25, 27, 29; largest is 29.

Pipes A and B can fill a tank in 12 and 18 hours respectively. If both are opened together, in how many hours will the tank be full?

Answer: 7.2 hours

Combined rate = 1/12 + 1/18 = 5/36 per hour; time = 36/5 = 7.2 hours.

A boat travels 30 km upstream in 5 hours and 30 km downstream in 3 hours. What is the speed of the current?

Answer: 2 km/h

Upstream speed = 6 km/h, downstream speed = 10 km/h; current = (10−6)/2 = 2 km/h.