Quantitative Aptitude Problems On Ages and Averages
What is average?
The concept of average is equal distribution of the overall value among all the things or persons present there. So the formula for finding the average is as follows:
Average, A = Total of all things, T / Number of things, N
Therefore, Total, T = AN
If any person joins a group with more value than the average of the group then the overall average increases. This is because the value in excess than the average will also be distributed equally among all the members.
Similarly when any value less than the average joins the group the overall group decreases as the deficit is divided equally among all the people present there.
Consider three people A, B and C with total of Rs. 30/-. Their average becomes Rs. 10/- for each. If another person D joins them with Rs. 50/- then he has Rs. 40/- more than actual average of Rs. 10/-.
So this Rs. 40/- will get distributed among those four and each gets Rs. 10/-. Thus the average becomes Rs. 20/- each.
The average age of a class of 30 students is 12. If the teacher is also included the average becomes 13 years. Find the teacher’s age.
When the teacher is included there are totally 31 members in the class and the average is increased by 1 year. This means that everyone got 1 extra year after distributing the extra years of the teacher.
So extra years of the teacher are as follow: 31×1=31 years.
Age of the teacher = actual avg + extra years = 12 + 31 = 43 years
Quantitative aptitude Problems on Averages and ages:
- The average of 13 papers is 40. The average of the first 7 papers is 42 and of the last seven papers is 35. Find the marks obtained in the 7th paper?
(D) None of these
- The average age of the Indian cricket team playing theNagpurtest is 30. The average age of 5 of the players is 27 and that of another set of 5 players, totally different from the first five, is 29. If it is the captain who was not included in either of these two groups, then find the age of the captain.
(D) Cannot be determined
- A bus goes toRanchifromPatnaat the rate of 60 km per hour. Another bus leavesRanchiforPatnaat the same times as the first bus at the rate of 70 km per hour. Find the average speed for the journeys of the two buses combined if it is known that the distance fromRanchitoPatnais 420 kilometers.
(A) 64.615 kmph
(B) 64.5 kmph
(C) 63.823 kmph
(D) 64.82 kmph
- A train travels 8 km in the first quarter of an hour, 6 km in the second quarter and 40 km in the third quarter. Find the average speed of the train per hour over the entire journey.
(A) 72 km/h
(B) 18 km/h
(C) 77.33 km/h
(D) 78.5 km/h
- The average weight of 6 men is 68.5 kg. If I is known that Ram and Tram weigh 60 kg each, find the average weight of the others.
(A) 72.75 kg
(B) 75 kg
(C) 78 kg
(D) None of these
- The average score of a class of 40 students is 52. What will be the average score of the rest of the students if the average score of 10 of the students is 61.
- The average age of 80 students of IIM,Bangaloreof the 1995 batch is 22 years. What will be the new average if we include the 20 faculty members whose average age is 37 years?
(A) 32 years
(B) 24 years
(C) 25 years
(D) None of these
- Out of the three numbers, the first is twice the second and three times the third. The average of the three numbers is 88. The smallest number is
- The sum of three numbers is 98. If the ratio between the first and second is 2 : 3 and that between the second and the third is 5 : 8, then the second number is
- The average height of 30 girls out of a class of 40 is 160 cm and that of the remaining girls is 156 cm. The average height of the whole class is
(A) 158 cm
(B) 158.5 cm
(C) 159 cm
(D) 157 cm
The problems,which 10 are from different models,try to solve them.while solving the problems on averages and ages in your exam,answer them in 40-45 sec,because of they are basically very easy problems and also the concepts of averages and ages are same.