Question 1

The average of first nine multiples of 3 is?

Accepted Answer

Average = ( 3 + 6 + 9 + 12 + 15 + 18 + 21 + 24 + 27 ) / 9 = 3(1+2+3+4+5+6+7+8+9)/9 = ( 45 / 3 ) = 15

Question 2

The average of five results is 46 and that of the first four is 45. the fifth result is?

Accepted Answer

Fifth result = sum of all five result - sum of first four result. = 5 x 46 - 4 x 45 = 230 -180 =50

Question 3

The average of 30 results is 20 and the average of other 20 results is 30 . what is the average of all the results?

Accepted Answer

Sum of 50 result = sum of 30 result + sum of 20 result. = 30 x 20 + 20 x 30 = 1200

Question 4

The average of numbers 0.64204, 0.64203, 0.64202 and 0.64201 is?

Accepted Answer

Average = (0.64204 + 0.64203 + 0.64202 + 0.64201)/ 4 =2.5681/ 4 =0.642025

Question 5

The average weight of A, B, C is 45kg. if the average weight of A and B be 40 kg and that of B and C be 40kg and that of B and C be 43kg, then the weight of B is?

Accepted Answer

weight of (A + B ) = (2 X 40 ) Kg = 80 kg weight of (B + C ) = (2 X 43) kg = 86 kg weight of (A + 2B +C ) = (80 + 86) kg = 166 kg weight of (A + B + C ) = (3 X 45) kg = 135 kg weight of B = (166-135) kg = 31 kg

Question 6

The average weight of 19 students is 15kg. by the admission of a new student the average weight is reduced to 14.8 kg. the weight of the new student is?

Accepted Answer

Weight of new student = Total weight of all 20 students - Total weight of initial 19 students = (20 x 14.8 - 19 x 15) kg = 11 kg.

Question 7

The average weight of 8 persons is increased by 2.5 kg, when one of them whose weight is 56 kg is replaced by a new man. The weight of the man is?

Accepted Answer

Total Increase = 8 x 2.5 = 20 kg. weight of new man = (56 + 20) kg = 76 kg

Question 8

The average of the daily income of A, B and C is Rs . 60 . If B earns Rs . 20 more than C and A earns double of what C earns. What is the daily income of C?

Accepted Answer

Let C's earning = Rs. y. Then, B's earning = Rs. (y + 20) and A's earning = Rs. 2y ∵ 2y + y + 20 + y= 3 x 60 ⇒ 4x = 160 ∴ x = 40

Question 9

The average age of an adult class is 40 years. 12 new students with an average age of 32 years join the class. Therefore decreasing the average by 4 year. what was the original strength of class?

Accepted Answer

Let original strength = y Then , 40y + 12 x 32 = ( y + 12) x 36 ⇒ 40y + 384 = 36y + 432 ⇒ 4y = 48 ∴ y = 12

Question 10

In a class, there are 20 boys whose average age is decreased by 2 months, when one boy aged 18 years is replaced by a new boy. The age of the new boy is?

Accepted Answer

Total decrease = ( 20 X 2 ) months = 3 years 4 month ∴ Age of the new boy = ( 18 years ) – ( 3 years 4 months) = 14 years 8 month

Question 11

Average monthly income of a family of 4 earning members was Rs. 735. One of the earning members died and therefore, the average income came down to Rs 650. The income of the deceased was?

Accepted Answer

Income of the deceased = Total income of 4 members - total income of remaining 3 members. = 735 x 4 - 650 x 3 Rs. = 990 Rs.

Question 12

The average age of 24 students in a class is 10. If the teacher's age is included, the average increase by one . The age of the teacher is?

Accepted Answer

Age of the teacher = Sum of age of 24 students and teacher - Sum of age of 24 students. = 25 x 11 - 24 x 10 = 35 years. ∴ Age of teacher = 35 years.

Question 13

The average expenditure of a man for the first five month is Rs. 120 and for the next seven months it is Rs . 130. if he saves Rs 299 in that year, his monthly average income is?

Accepted Answer

Total income = total expenditure + total saving = Rs. (120 X 5 + 130 X 7 + 290) =Rs. 1800 Average monthly income =1800 / 12 =150 Rs.

Question 14

The average salary of 20 workers in an office id Rs. 1900 per month . If the manger's salary is added , the average salary become Rs. 2000 p.m what is the manager's annual salary?

Accepted Answer

Manager's salary per month = Rs. ( 21 x 2000 - 20 x 1900 ) = Rs. 4000 ∴ Manager 's annual salary = Rs. (4000 X 12 ) = Rs. 48000.

Question 15

The average of 6 observation is 12. A new 7th observation is included and the new average is decrease by 1 , the seventh observation is?

Accepted Answer

Seventh observation = sum of 7 observations - sum of 6 observations = 7 x 11 – 6 x 12 = 5

Question 16

Out of four number, the average of first three is 15 and that of the last three is 16, if the last number is 19, the first is?

Accepted Answer

Sum of four number = ( 15 x 3 + 19 ) = 64 Sum of last three number = ( 16 x 3 ) = 48 ∴ first number = ( 64 – 48 ) = 16

Question 17

The average temperature of the first three days is 27° C and that of the next three is 29° C . If the average of the whole week is 28.5° C, the temperature of the last day of the week is?

Accepted Answer

Temperature of last day = Sum of temperature of 7 days - sum of temperature of first 6 days. = ( 7 x 28.5 ) - [( 3 x 27 ) + ( 3 x 29 )] =31.5 ∴ Temperature of last day = 31.5

Question 18

A ship sails out to a mark at the rate of 15 kmph. and sails back at the rate of 10 kmph. The average rate of sailing is?

Accepted Answer

Average = ( 2uv / u +v ) km/hr = ( 2 x 15 x 10 ) / (15 +10 ) km/hr. = 12 km/hr.

Question 19

The average consumption of petrol for a car for seven months is 110 litres and for next five months it is 86 litres. The average monthly consumption is?

Accepted Answer

Average = ( sum of consumption of petrol in first 7 months + sum of consumption of petrol in last 5 months. ) / 12 Average = ( 110 x 7 + 86 x 5 ) / 12 =(1200 / 12 = 100 liters

Question 20

A batsman has a certain average runs for 11 innings . In the 12th innings he made a score of 90 runs and thereby decrease his average by 5 . His average after 12th innings is?

Accepted Answer

Let the average for first 11 innings is y From question 11y + 90 = (y - 5) x 12 ⇒ y = 150 ∴ Average after 12th inning = (150 - 5)= 145

Average Questions