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:

Sriram was conducting an experiment in which the average of 11 observations came to be 92, while the average of first five observations was 89, and that of the last five was 86. What was the measure of the 6th observation ? 

A) 134 B) 137
C) 139 D) 141
 
Answer & Explanation Answer: B) 137

Explanation:
This can be done as,
 
(11 × 92)  -  (5 × 89)  -  (5 × 86) 
 
= 1012- 445 - 430 = 137
Report Error

View Answer Report Error Discuss

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

11 6125
Q:

If the average height of boys in a hall is 180 cm and that of girls is 150 cm. If the average height of the gathering is 165 cm, then find the number of girls present in the hall if the number of boys present in the hall are 78 ?

A) 56 B) 64
C) 87 D) 78
 
Answer & Explanation Answer: D) 78

Explanation:

Using Trial and error method,

we get the number of girls in the hall = 78

Report Error

View Answer Report Error Discuss

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

27 5515
Q:

Navaneet has thrice the money Poonam has and Poonam has 25% more money than Hebah. If the average money of the three is Rs. 350, What is the amount that Navaneet has ?

A) Rs. 175 B) Rs. 220.75
C) Rs. 218.55 D) Rs. 656.25
 
Answer & Explanation Answer: D) Rs. 656.25

Explanation:

Assume Hebah has Rs. M

Since 25% more money at Poonam

=> Money at Poonam = M + (25% of M)

=> Money at Poonam = M + 0.25M = Rs. 1.25M

Money with Navaneet is thrice the money with Poonam,

=> Money at Navaneet = 3(1.25M) = Rs. 3.75M

Now, sum of all Money = (M + 1.25M + 3.75M) = Rs. 6M

But given the average of the money is Rs. 350

=> 6M/3 = 350

=> 2M = 350

=> M = 350/2 = Rs. 175

=> Amount of money Navaneet has = Rs. 3.75M = 3.75 x 175 = Rs. 656.25.

Report Error

View Answer Report Error Discuss

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

22 5433
Q:

The average score of boys in an examination in a school is 81 and that of the girls is 83 and the average score of the school is 81.8. Then what will be ratio between the number of girls to the number of boys, in the examination?

A) 3:2 B) 2:3
C) 4:3 D) 3:4
 
Answer & Explanation Answer: B) 2:3

Explanation:

Let the number of boys = b

Let the number of girls = g

From the given data,

 

81b + 83g = 81.8(b + g)

81.8b - 81b = 83g - 81.8g

0.8b = 1.2g

b/g = 1.2/0.8 = 12/8 = 3/2

=> g : b = 2 : 3

 

Hence, ratio between the number of girls to the number of boys = 2 : 3.

Report Error

View Answer Report Error Discuss

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

24 4715
Q:

In a particular week the average number of people who visited the Park is 40. If we exclude the holidays then the average is increased by 16. Further if we exclude also the day on which the maximum number of 112 people visited the Park, then the average becomes 42. The number of holidays in the week is

A) 1 B) 2
C) 3 D) 4
 
Answer & Explanation Answer: B) 2

Explanation:
Total number of people = 40 * 7 = 280
(7 -n)*(40+16) = 280 
(7 -n)*56 = 280

7-n = 5

Number of holidays = 2

Report Error

View Answer Report Error Discuss

Filed Under: Average
Exam Prep: Bank Exams

4 4125
Q:

The average marks of 50 students in an examination was 65. It was later found that the marks of one student had been wrongly entered as 83 instead of 38. The correct average is?

A) 63.9 B) 64.5
C) 64.7 D) 64.1
 
Answer & Explanation Answer: D) 64.1

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Average
Exam Prep: Bank Exams

1 3736
Q:

Find the average of first 50 natural numbers?

A) 25 B) 25.5
C) 26 D) 26.5
 
Answer & Explanation Answer: B) 25.5

Explanation:

We Know that sum of the n natural numbers =n(n+1)2

  

Then sum of 50 natural numbers= 50(51)2= 1250

  

Average of the 50 natural numbers = 125050 = 25.5

Report Error

View Answer Report Error Discuss

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

22 3258
Q:

The average of 50 consecutive natural numbers is x. What will be the are average when the next four natural numbers are also included?

A) x + 1 B) x + 2
C) x + 4 D) x + (x/54)
 
Answer & Explanation Answer: B) x + 2

Explanation:
Sum of n consecutive natural numbers = n(n+1)/2
Average of n consecutive natural numbers = (n+1)/2
For first 50 average = 51/2 = x
Last 50 average = 55/2 = x+2
Report Error

View Answer Report Error Discuss

Filed Under: Average
Exam Prep: Bank Exams

2 3156