Average (2)

1. The average age of a class of 22 students is 21 years. The average increased by 1 when the teacher’s age also included. What is the age of the teacher?
1. 48
2. 45
3. 43
4. 44

Answer & Explanation

Answer:- 4

Explanation :-

Average age of 22 students = 21 years
Sum of ages of all students = 21 * 22 = 462
Average age of 20 students + 1 teacher = 22 years
Total afe of 22 students and teacher (23 persons) = 22 * 23 = 506
Age of teacher = 506 – 420 = 44

 

2. A grocer has a sale of Rs. 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs. 6500?
1. 4800
2. 4991
3. 5004
4. 5000

Answer & Explanation

Answer:- 2

Explanation :-

Let the Sixth Sale be  Rs. x
Required Average = Rs. 6500
(6435 + 6927 + 6855 + 7230 + 6562 + x ) / 6 = 6500
(6435 + 6927 + 6855 + 7230 + 6562 + x ) = 6500 * 6
(6435 + 6927 + 6855 + 7230 + 6562 + x ) = 39000
x = 39000 – 34009 =  4991

 

3. The average of 20 numbers is zero. Of them, How many of them may be greater than zero, at the most?
1. 1
2. 20
3. 0
4. 19

Answer & Explanation

Answer:- 4

Explanation :-

Average of 20 numbers = 0
So,Sum of 20 numbers = 0
Therefore , At the most, there can be 19 positive numbers.
If the sum of these 19 positive numbers is x, 20th number will be -x

 

4. The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. Find out the average age of the team.
1. 23 years
2. 20 years
3. 24 years
4. 21 years

Answer & Explanation

Answer:- 1

Explanation :-

Let the Average age of the team = x years
11x – (26 + 29) = 9(x -1)
11x – 9x = 46
2x = 46
x = 23

 

5. The average monthly income of A and B is Rs. 5050. The average monthly income of B and C is Rs. 6250 and the average monthly income of A and C is Rs. 5200. What is the monthly income of A?
1. 2000
2. 3000
3. 4000
4. 5000

Answer & Explanation

Answer:- 3

Explanation :-

P + Q = (5050 x 2) = 10100
Q + R = (6250 x 2) = 12500
P + R = (5200 x 2) = 10400
By adding these
P + Q + Q + R + P + R = 10100 + 12500 + 10400
2(P + Q + R) = 33000
P + Q + R = 16500
we know Q + R = 12500
Therefore   P = 16500 – 12500 = 4000

 

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