Question 1

The Average of 100, 200, 300, 400, ... , 1000 is 550. If each number is divided by 5, then the new average will be equal to

Accepted Answer

Actual average =( 100 + 220 + 300 + ... + 1000 ) / 10 =550 New Average = 550 / 5 =110

Question 2

A, B, C, D, E are the five electronic shops in the Naza market, which have 20, 30, 60, 80 and 50 T. V . sets with them respectively, then the average number of T. V. sets in each shop is

Accepted Answer

Average number of T. V. sets = ( 20 + 30 + 60 + 80 + 50 ) / 5 = 48

Question 3

A, B, C, D, E, F are the only six families in Indira Nagar. A, B, C, D, E and F has 7, 8, 10, 13, 6, and 10 member in their families respectively. If 1 member from all the six families left their respective families to accommodate themselves in the …

Accepted Answer

Required average = (( 7 - 1 ) + ( 8 - 1 ) + ( 10 - 1 ) + ( 13 - 1 ) + (6 - 1) +( 10 - 1 ) )/ 6 = ( 7 + 8 +10 + 13 + 6 + 10 ) / 6 - ( 6 x 1 ) / 6 =9 - 1 = 8

Question 4

The average number of shirts with Salman, Ambani and Dalmiya is 60, if all of them reached a shopping mall in Delhi and purchased 6 shirts each of them then average number of shirt each of them now has

Accepted Answer

Required average = Old average + New average = 60 + 6 = 66

Question 5

In a flower shop there were 6 flowers in each bouquet. If the seller has doubled the number of flowers in each bouquet then the new average of flowers in each bouque is

Accepted Answer

Now required average = old average x Multiplicand = 6 x 2 = 12

Question 6

The average salary of A, B is Rs. 6000 and that of C, D and E is Rs. 8000. The average salary of all the 5 people is

Accepted Answer

Required average salary = ( 6000 x 2 + 8000 x 3) / (2 + 3 ) = 36000 / 5 = Rs. 7200

Question 7

The average salary of Rajesh, Bahadur and Amir is Rs. 8000 per month. The average expenditure of Rajesh , Bahadur and Amir per month is Rs. 5000. The average savings of all the 3 persons per month is

Accepted Answer

Average saving = Average Income - Average Expenditure = 8000 - 5000 = 3000

Question 8

The average salary of A, B and C is Rs.10,000 and average expenditure of A is Rs. 6000 then the average savings of B and C is

Accepted Answer

Total income = Total expenditure + Total savings We are not find the average savings of B and C, Since data is insufficient.

Question 9

The average salary of all the 60 employees in an office is Rs. 12,000 per month. if the number of executives is twice the number of non executives employees, then the average salary of all the non executives employees is

Accepted Answer

No. of executives / No. of non- executives = 2 / 1 Therefore Number of executives = 40 and number of non executives employees = 20 now , go through the options Total salary = 40 x salary of executives + 20 x salary of non-executives 60 x 12000 = 40 x k + 20 x l, here k, l are unknowns so we con't determine the required average salary

Question 10

Einstein goes from Ahmedabad To Lucknow at the speed of 40 km/hr and returned at the speed of 60 km/hr .the average speed of Einstein during the whole journey is

Accepted Answer

Average speed =2 x 40 x 60 / ( 40+ 60) = 4800 / 100 = 48 km/hr

Question 11

The average age of A,B,C,D and E is 40 years.The average age of A and B is 35 years and the average age of C and D is 42 years .The age of E is

Accepted Answer

Age E = ( A + B + C + D + E ) - [ ( A + B ) + ( C + D ) ] = ( 40 x 5 ) - [ ( 35 x 2 ) + ( 42 x 2 )] =200 - ( 70 + 84) = 200 - 154 = 46

Question 12

Find the average of 308, 142, 160, 245 and 25.

Accepted Answer

sum of observations = 308 + 142 + 160 245 + 25 = 880 Average = Sum of all observations / Number of observations =880 / 5 =176

Question 13

The average age of a group of 10 friends is 15 yr. If one friend leaves the group, the average becomes 16 yr. Find the age of the friend who left the group.

Accepted Answer

Age of friend left = Previous average of the age - Number of persons present x Increase in average age = 15 - ( 10-1 ) x ( 16-15 ) = 15- 9 x 1 = 15 - 9 = 6yr

Question 14

What is the average of first 79 natural numbers?

Accepted Answer

Average of first n natural numbers = ( n + 1 ) / 2 = ( 79 + 1 ) / 2 = 40

Question 15

The average of 8 number 21. if each of the number is multiplied by 8,the new set of number is?

Accepted Answer

Average will increase by 8 times. So average of new members = (21 x 8 ) = 168

Question 16

The average of 50 number is 38 .if two numbers 45 and 55 are discarded , the average of the remaining number is?

Accepted Answer

Sum of 50 member = (50 x 38 ) = 1900 Sum of 48 member = [1900- (45 + 55 ) ] = 1800 ∴ Required Average = 1800/48 = 225/6 = 37.5

Question 17

The average score of a cricketer for 10 matches is 43.9 runs. If the average for the first six matches is 53 , the average for the last four matches is?

Accepted Answer

Let the average for last 4 matches be y. Sum of score for 10 matches = sum of score for first 6 matches + sum of score of last 4 matches. So 53 x 6 + 4y = 10 x 43.9 ∴ 4x= 439-318 ⇒4x= 121 ∴ x= 30.25

Question 18

The average height of 30 girls out of a class of 40 is 160 cms and that of the remaining girls is 156 cms. the average height of the whole class is?

Accepted Answer

Average height of the whole class = sum of height of 40 girls / 40 = (30 x 160 + 10 x 156) / 40 = 159 cms.

Question 19

If a, b, c, d, e are five consecutive odd number , their average is?

Accepted Answer

Since a, b, c, d, e are 5 consecutive numbers so b = a + 2. c = a + 4. d = a + 6. e = a + 8. Average = (a + b + c + d + e)/ 5 = [a + (a + 2 ) + (a +4 ) + (a+6 )+ (a+8)] / 5 = (5a+20) / 5 = a + 4

Question 20

Out of three numbers, the first is twice the second and is half of the third. If the average of three number is 56, the three number in order are?

Accepted Answer

Let second number = x So, first number = 2x and third number= 4x ∴ ( x + 2x + 4x ) / 3 = 56 ⇒ 7x = 168 ⇒ x = 24 So the numbers are 48,24, 96,

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