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:

 The average age of 8 men is increased by years when two of them whose ages are 21 years and 23 years are replaced by two new men. The average age of the two new men is :

A) 20 B) 30
C) 40 D) 50
 
Answer & Explanation Answer: B) 30

Explanation:

Total age increased = (8 * 2) years = 16 years.

Sum of ages of two new men = (21 + 23 + 16) years = 60 years

Average age of two new men = (60/2) years = 30 years.

Report Error

View Answer Report Error Discuss

84 38704
Q:

The average age of a husband and his wife was 23 years at the time of their marriage. After  five years they have a one-year old child. The average age of the family now is : 

A) 25 B) 23
C) 19 D) 18
 
Answer & Explanation Answer: C) 19

Explanation:

Sum of the present ages of husband, wife and child = (23 * 2 + 5 * 2) + 1 = 57 years.

Required average = (57/3) = 19 years.

Report Error

View Answer Report Error Discuss

78 37205
Q:

Of the four numbers, whose average is 60, the first is one-fourth of the sum of the last three. The first number is :

A) 17 B) 29
C) 36 D) 48
 
Answer & Explanation Answer: D) 48

Explanation:

Let the first number be x,

Then, sum of the four numbers = x + 4x = 5x.

so,  5x/4 = 60 or x = (60 * 4) / 5 = 48.

Report Error

View Answer Report Error Discuss

115 36865
Q:

The average salary of all the workers in a workshop is Rs. 8000. The average salary of 7 technicians is Rs. 12000 and the average salary of the rest is Rs. 6000. The total number of workers in the workshop is :

A) 20 B) 21
C) 23 D) 24
 
Answer & Explanation Answer: B) 21

Explanation:

 Lot the total number of workers be v Then,

8OOOv = (12000 * 7) + 6000 (v - 7) <=>  2000v = 42000  <=>  v = 21.

Report Error

View Answer Report Error Discuss

64 34561
Q:

A team of 8 persons joins in a shooting competition. The best marksman scored 85 points. If he had scored 92 points, the average score for the team would have been 84. The number of points, the team scored was :

A) 665 B) 657
C) 658 D) 678
 
Answer & Explanation Answer: A) 665

Explanation:

Let the total score be x.

(x + 92 - 85) / 8 = 84.

So,  x + 7 = 672   => x = 665.

Report Error

View Answer Report Error Discuss

58 33158
Q:

A certain factory employed 600 men and 400 women and the average wager was Rs. 25.50 per day, If a woman got Rs. 5 less than a man, then what are their daily wages ?

A) m:25.50 w:27.50 B) m:27.50 w:22.50
C) m:26.50 w:27.50 D) m: 24.50 w:26.50
 
Answer & Explanation Answer: B) m:27.50 w:22.50

Explanation:

Let the daily wage of a man be Rs. x.

Then, daily wage of a woman = Rs. (x - 5).

Now, 600x + 400 (x - 5) = 25.50 * (600 + 400) <=>  1000x = 27500 <=>  x = 27.50.

Man's daily wages = Rs. 27.50; Woman's daily wages = (x - 5) = Rs. 22.50.

Report Error

View Answer Report Error Discuss

54 32680
Q:

Out of 9 persons, 8 persons spent Rs. 30 each for their meals. The ninth one spent Rs. 20 more than the average expenditure of all the nine. The total money spent by all of them was : 

A) Rs. 292.50 B) Rs. 297.50
C) Rs. 298 D) Rs. 298.50
 
Answer & Explanation Answer: A) Rs. 292.50

Explanation:

Let the average expenditure be Rs. x Then,

 

9x=[(8*30)+(x+20)]<=>9x =x+260 <=> x =32.50

 

Total money spent = 9x =  Rs. (9 x 32.5O) = Rs 292. 50

Report Error

View Answer Report Error Discuss

95 32327
Q:

A batsman in his 17th innings makes a score of 85 and their by increasing his average by 3. What is his average after the 17th innings ?

A) 34 B) 36
C) 35 D) 37
 
Answer & Explanation Answer: D) 37

Explanation:

16x + 85 = 17(x + 3)

x = 34 + 3 = 37

Report Error

View Answer Report Error Discuss

40 30554