FACTS  AND  FORMULAE  FOR  AVERAGE QUESTIONS

 

 

1. Average =Sum of observationsNo. of observations

2. Suppose a man covers a certain distance x kmph and an equal distance at y kmph. Then, the average speed during the whole journey is2xyx+yKmph

Q:

Amithab's average expenditure for the January to June is Rs. 4200 and he spends Rs.1200 in January and Rs.1500 in july.The average expenditure for the months of febraury to July is:

A) Rs. 4250 B) Rs. 4520
C) Rs. 4060 D) None of these
 
Answer & Explanation Answer: A) Rs. 4250

Explanation:

Amithab's total expenditure for Jan - June  = 4200 x 6 = 25200

 

Expenditure for Feb - June = 25200-1200 = 24000

 

Expenditure for the months of Feb - July = 24000 + 1500 =25500

 

The average expenditure = 25500/6 = 4250

Report Error

View Answer Report Error Discuss

Filed Under: Average

9 10573
Q:

8 years ago there were 5 members in the Arthur's family and then the average age of the family  was 36 years. Mean while Arthur got married and gave birth to a child. Still the average age of his family is same now. What is the age of his wife at the time of his child's birth was.If the difference between the age of her  child and herself was 26 years.

A) 25 years B) 26 years
C) 20 years D) can't be determined
 
Answer & Explanation Answer: B) 26 years

Explanation:

Since we know that the difference b/w the age of any two persons remains always constant, while the ratio of their ages gets changed as the time changes.

 

so, if the age of his child be x (presently)

 

Then the age of  wife be x + 26 (presently)

 

Thus the total age = x + ( x + 26) = 32  [252-220 =32]

=> x = 3

Therefore, The age of her child is 3 years and her self  is 29 years. Hence her age at the time of the birth of her child was 26 years.

Report Error

View Answer Report Error Discuss

Filed Under: Average

11 10471
Q:

The average monthly salary of the employees of a firm is Rs.60 out of the employees 12 officers get an average of Rs.400 per month and the rest an average of Rs. 56 per month , Find the number of emp

Answer

Actual average salary of 12 officers = 400


\inline \fn_jvn \therefore Total salary of 12 officers = 400 x 12 = 4800


Average of these 12  officers as a whole =60


Total salary of 12 officers as a whole = 60 x 12 = 720


The total salary of rest  = 4800 - 720 = 4080


Difference in average of the rest of officers  = 60 - 56 = 4


Rest of the officers = \inline \fn_jvn \frac{4080}{4}=1020


Total number of employees = 1020 + 12 = 1032

Report Error

View answer Workspace Report Error Discuss

Subject: Average

51 10317
Q:

Five boxes of bananas sell for Rs. 30. how many boxes can you buy for Rs.9?

A) 2 B) 1.5
C) 1.25 D) 2.5
 
Answer & Explanation Answer: B) 1.5

Explanation:

Given Five boxes of bananas sell for Rs. 30.

=> 1 Box of Bananas for = 30/5 = Rs. 6

 

Then, for Rs. 9

=> 9/6 = 3/2 = 1.5

 

Hence, for Rs. 9, 1.5 box of bananas can buy.

Report Error

View Answer Report Error Discuss

Filed Under: Average
Exam Prep: AIEEE , Bank Exams , CAT , GATE
Job Role: Analyst , Bank Clerk , Bank PO , Database Administration

25 10127
Q:

There are 100 students in 3 sections A, B and C of a class. The average marks of all the three sections was 84. The average of B and C was 87.5 and the average marks of students in A section was :

A) 20 B) 35
C) 54 D) 40
 
Answer & Explanation Answer: A) 20

Explanation:

Numbers of students in section A = x
∴ Numbers of students in section B and C = (100 – x)
∴ x 70 + (100 – x) 87.5 = 84 100
=> 70x + 87.5 100 – 87.5x = 8400
=> 8750 – 17.5x = 8400
=> 17.5x = 8750 – 8400 => x = 20.

Report Error

View Answer Report Error Discuss

Filed Under: Average
Exam Prep: AIEEE , Bank Exams , CAT , GATE
Job Role: Analyst , Bank Clerk , Bank PO , IT Trainer

24 9998
Q:

The average of the two-digit numbers, which remain the same when the dibits inter-change their positions, is :

A) 53 B) 54
C) 55 D) 56
 
Answer & Explanation Answer: C) 55

Explanation:

Average = (11 + 22 + 33 + 44 + 55 + 66 + 77 + 88 + 99) / 9

             =( (11 + 99) + (22 + 88) + (33 + 77) + (44 + 66) + 55) / 9

             = (4 * 110 + 55)/9 =  495 / 9 = 55. 

Report Error

View Answer Report Error Discuss

Filed Under: Average

10 9964
Q:

The average of 9 results is 50. The average of first four results is 52 and average of last four results is 49 . what is the fifth result?

Answer

Total of results = 50 x 9 = 450


Total of first four results = 52 x 4 = 208


Total of Last four results = 49 x 4 = 196


Hence the fifth result = 450 - (208 + 196) = 46

Report Error

View answer Workspace Report Error Discuss

Subject: Average

20 9905
Q:

The average of 26,29,n,35 and 43 lies between 25 and 35. If n is always an integer and greater than the average  of the given integers then the value of n is :

A) 33 B) 34
C) 33 D) None of these
 
Answer & Explanation Answer: C) 33
Explanation:

Average of 26,29,35 and 43 is 33.25 . Also the average of 26 , 29, n, 35 and 43 lies between 25 and 35 i.e,

 25<26+29+n+35+435<35 

=> 125 < 26+29+n+35+43 < 175 

=> 125 < 133 + n < 175

=> n < 42

 Since the value of n is an integer and greater than 33.25 then 33 < n < 42 for every integer n.

Report Error

View Answer Report Error Discuss

Filed Under: Average

9 9803