Average - Aptitude MCQ Questions and Solutions with Explanations

71

The average age of 3 children in a family is 20% of the average age of the father and the eldest child. The total age of the mother and the youngest child is 39 years. If the father's age is 26 years, what is the age of the second child ?

A) 15 years B) 18 years C) 20 years D) Cannot be determined

Discuss

Answer & Solution

Answer: Option D

Solution:

Since the total or average age of all the family members is not given, te given data is inadequate. So, the age of the second child cannot be determined.

72

Five years ago the average age of A, B, C, D was 45 years. By including X the present average of all the five is 49 years. Them the present age of X is-

A) 40 years B) 45 years C) 48 years D) 64 years

Discuss

Answer & Solution

Answer: Option B

Solution:

Sum of the present ages of A, B, C and D
= (45 × 4 + 5 × 4) years
= 200 years
Sum of the present ages of A, B, C, D and X
= (49 × 5) years
= 245 years
∴ X's present age
= (245 - 200) years
= 45 years

73

A cricketer whose bowling average is 12.4 runs per wicket takes 5 wickets for 26 runs and thereby decreased his average by 0.4. The number of wickets taken by him the last match was-

A) 64 B) 72 C) 80 D) 85

Discuss

Answer & Solution

Answer: Option D

Solution:

Let the number of wickets taken till the last match be x
$$\eqalign{ & \Rightarrow \frac{{12.4x + 26}}{{x + 5}} = 12 \cr & \Rightarrow 12.4x + 26 = 12x + 60 \cr & \Rightarrow 0.4x = 34 \cr & \Rightarrow x = \frac{{34}}{{0.4}} \cr & \Rightarrow x = \frac{{340}}{4} \cr & \Rightarrow x = 85 \cr} $$

74

The average of 11 players of a cricket team is decreased by 2 months when two of them aged 17 years and 20 years are replaced by two new players. The average age of the new players is-

A) 17 years 1 month B) 17 years 7 months C) 17 years 11 months D) 18 years 3 months

Discuss

Answer & Solution

Answer: Option B

Solution:

Total age decreased
= (11 × 2) months
= 22 months
= 1 year 10 months
∴ Average age of two new players
$$\left( {\frac{{{\text{35 years 2 months}}}}{2}} \right)$$
= 17 years 7 months

75

The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is-

A) Rs. 3500 B) Rs. 4000 C) Rs. 4050 D) Rs. 5000

Discuss

Answer & Solution

Answer: Option B

Solution:

Let P, Q and R represent their respective monthly income
Then, we have
P + Q = (5050 × 2) = 10100.....(i)
Q + R = (6250 × 2) = 12500.....(ii)
P + R = (5200 × 2) = 10400.....(iii)
Adding (i), (ii) and (iii), we get
2 (P + Q + R) = 33000
⇒ P + Q + R = 16500
Subtracting (ii) from (iv), we get P = 4000
∴ P's monthly income = Rs. 4000

76

The average of the ages of Sumit, Krishna and Rishabh is 43 and the average of the ages of Sumit, Rishabh and Rohit is 49. If Rohit is 54 years old, what is Krishna’s age?

A) 24 years B) 36 years C) 45 years D) Cannot be determined E) None of these

Discuss

Answer & Solution

Answer: Option B

Solution:

Sumit + Krishna + Rishabh = 43 × 3 = 129.....(i)
Sumit + Rishabh + Rohit = 49 × 3 = 147.....(ii)
Subtracting (i) from (ii), we get:
Rohit - Krishna = 18
⇒ Krishna = 54 - 18 = 36

77

A library has an average of 510 visitors on Sundays and 240 on other days. What is the average number of visitors per day in the month of June beginning with a Sunday?

A) 276 B) 280 C) 285 D) 250

Discuss

Answer & Solution

Answer: Option C

Solution:

If a month beings with Sunday then there are 5 Sundays in that month.
Total number of visitors comes on Sunday
= 510 × 5 = 2550
Total number of visitors come on other days
= 240 × 25 = 6000
∴ Average number of visitor per day
$$\eqalign{ & = \frac{{2550 + 6000}}{{30}} \cr & = \frac{{8550}}{{30}} \cr & = 285 \cr} $$

78

Average of a, b, and c is 11; average of c, d and e is 17; average of e and f is 22 and average of e and c is 17. Find out the average of a, b, c, d, e and f.

A) $$15\frac{2}{3}$$ B) $$18\frac{1}{2}$$ C) $$16\frac{1}{2}$$ D) None of these

Discuss

Answer & Solution

Answer: Option A

Solution:

Average of a, b and c = 11
Total of a, b and c = 33.....(i)
Similarly, average of c, d and e = 17
Sum of c + d + e = 3 × 17 = 51.....(ii)
Average of e and f is 22
Sum of e + f = 2 × 22 = 44.....(iii)
Average of e and c is 17
Sum of e + c = 2 × 17 = 34.....(iv)
By equations (i) + (ii) + (iii) - (iv)
a + b + c + c + d + e + e + f - e - c
= 33 + 51 + 44 - 34
= 128 - 34
= 94
∴ Required average
= $$\frac{94}{6}$$
= $$\frac{47}{3}$$
= $$15\frac{2}{3}$$

79

The average of 6 numbers is 7. The average of three numbers of them is 5. What will be the average of remaining numbers?

A) 15 B) 30 C) 9 D) 42

Discuss

Answer & Solution

Answer: Option C

Solution:

Average of 6 numbers = 7
Sum of 6 numbers = 6 × 7 = 42
Average of three numbers = 5
Sum of three numbers = 5 × 3 = 15
∴ Sum of the remaining three numbers
= 42 - 15 = 27
∴ Required average
= $$\frac{27}{3}$$
= 9

80

Find the average of 205, 302, 108, 403, and 202-

A) 450 B) 1125 C) 244 D) 1220

Discuss

Answer & Solution

Answer: Option C

Solution:

Sum of numbers
= 205 + 302 + 108 + 403 + 202
= 1220
∴ Required average
= $$\frac{1220}{5}$$
= 244