Problems on Averages - Aptitude Questions and Answers

Problems on Averages Questions and Answers

Learn and practice the chapter "Problems on Averages" with these solved Aptitude Questions and Answers. Each question in the topic is accompanied by a clear and easy explanation, formulae, shortcuts and tricks that help in understanding the concept.

Use of Problems on Averages

The questions and examples given in this section will be useful to all the freshers, college students and engineering students preparing for placement tests or any competitive exam like MBA, CAT, MAT, SNAP, MHCET, XAT, NMAT, GATE, Bank exams - IBPS, SBI, RBI, RRB, SSB, SSC, UPSC etc.

Practice with this online test to crack your placements and entrance tests!
1. Kritika is on a 4 days trip with school mates. She had decided to keep her average expense for 4 days at Rs 80. However, at the end of third day she realized that her expenses on first three days were Rs 80, Rs 90, Rs 110 and respectively. How much should she spend on 4th day to ensure that she meets her targeted average expense?

a. Rs. 40
b. Rs. 60
c. Rs. 90
d. Rs. 220

Answer: a. Rs. 40

Explanation:

Average=Sum of Observations
Number of Observations


Average=80+90+110+ 4th day=80
4

∴ 4th day expenditure = Rs. (320 - 280) = Rs 40


2. Find average of natural numbers from 1 to 67?

a. 33.5
b. 34
c. 50
d. 67

Answer: b. 34

Explanation:

Tip:
Average of first n natural numbers=(n+1)
2

Average of first n even numbers = n+1

Average of first n odd numbers = n


Average of natural numbers from 1 to 65=67+1=34
2


3. What is average of 7 runs, 9 runs, 11 runs, …., 27 runs, 29 runs and 31 runs?

a. 15
b. 16
c. 16.5
d. 19

Answer: d. 19

Explanation:

Tip:
Average of even numbers in 1 to n=Last even number+2
2

Average of odd numbers in 1 to n=Last odd number+1
2

Average of consecutive numbers=First number+ Last number
2


Here the difference between numbers is constant = 2.

So this can be called a consecutive series.

∴ Average=31+7=19
2


4. How much will be the average of the squares of natural numbers from 1 to 40?

a. 273.33
b. 553.5
c. 820
d. None of the above

Answer: b. 553.5

Explanation:

Tip:
Average of squares of first 'n' natural numbers=(n+1)(2n+1)
6

Average of cubes of first 'n' natural numbers=n(n+1)2
4


n = 40

Average of squares of numbers from 1 to 40=(40+1)(80+1)=41 x 81=553.5
66


5. The average of first 19 multiples of 12 is

a. 110
b. 110.5
c. 120
d. 220

Answer: c. 120

Explanation:

Tip:
Average of 'n' multiples of any number =  Number x(n+1)
2

IMPORTANT NOTE -
It is similar to average of first n natural numbers.  
Just multiply by the number as shown above.


Here n = 19

Average of 19 multiples of 12 = 12 x(19+1)=120
2