Quantitative Aptitude

Averages

1,527 Questions
All Basic average and reverse calculation 405 Adding or removing an observation 342 Weighted and combined averages 320 Replacement and correction of a recorded value 233 Ratio shortcut for two-group mixtures 111 Equal-distance average speed 59 Age, score, weight, and spending applications 32 Consecutive terms and arithmetic progressions 25

Averages Questions

Multiple choice

Amit selected three numbers randomly. He found that the average of three numbers is 32 , however he also noticed that if he increases the smaller number by 12 and reduce the largest number by 3 while the order remain same average becomes 5 less than the middle number , then find the middle number:

  1. 30

  2. 35

  3. 40

  4. 50
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the numbers be a, b, c. (a+b+c)/3 = 32 => a+b+c = 96. New average: (a+12 + b + c-3)/3 = b - 5. => a+b+c+9 = 3b - 15. => 96 + 9 = 3b - 15 => 105 + 15 = 3b => 120 = 3b => b = 40.

Multiple choice

In State Y, Ms. Patel's tenth-grade class of 25 students was surveyed, and 36% reported eating breakfast every day. The average tenth-grade class size in the state is also 25 students. Assuming Ms. Patel's class is representative of all tenth graders in the state, and there are 2,200 tenth-grade classes, about how many students in the state do not eat breakfast every day?

  1. 19,800

  2. 22,000

  3. 35,200

  4. 48,400
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

36% eat breakfast, so 64% do not. In a class of 25, 0.64 * 25 = 16 students do not eat breakfast. Total classes = 2200. Total students not eating = 2200 * 16 = 35,200.

Multiple choice

Sarah rides her bike around a triangular track, with each side measuring 5 kilometres. She covers the first side at a speed of 40 km/h and increases her speed by 5 km/h on each subsequent side. If she completes the entire triangular route, what is her average speed for the journey?

  1. 39.45 km/h

  2. 47.74 km/h

  3. 44.63 km/h

  4. 52.25 km/h

  5. a
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total distance is 15 km. Time for each side: t1 = 5/40 = 0.125 h, t2 = 5/45 = 0.111 h, t3 = 5/50 = 0.1 h. Total time = 0.3361 h. Average speed = 15 / 0.3361 = 44.63 km/h.

Multiple choice

A goods train runs 668 meters, 127 meters, 208 meters, 312 meters and 535 meters respectively in the first five minutes, and for the next five minutes maintains an average speed of 36 km per hour. The average speed of the train per hour during this period was

  1. 28.6 km/hr

  2. 31.4 km/hr

  3. 29.1 km/hr

  4. 18.8 km/hr
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total distance in the first 5 minutes is 668 + 127 + 208 + 312 + 535 = 1850 meters (1.85 km). In the next 5 minutes at 36 km/hr, the train travels (36/60) * 5 = 3 km. Total distance = 4.85 km in 10 minutes (1/6 hour). Average speed = 4.85 / (1/6) = 29.1 km/hr.