RRB NTPC - Averages (200 Questions with Explanation): Quantitative Aptitude Test

201.

The average age of a group of 10 students was 26. The average age increased by 1 years when two new students joined the group. What is the average age of the two new students who joined the group?

   A.) 22
   B.) 32
   C.) 21
   D.) 41

Answer: Option 'B'

The average age of a group of 10 students is 26.
Therefore, the sum of the ages of all 10 of them
= 10 × 26
= 260
When two students joins the group, the average increase by 1.
New Average = 27
Now there are 12 students Therefore, sum of all the ages of 12 students
= 12 × 27
= 324
Therefore, the sum of the ages of two students who joined
= 324 - 260
= 64
And the average age of these two students
= 64 / 2
= 32.

202.

Find the average of first 17 multiples of 3

   A.) 6.33
   B.) 27
   C.) 20
   D.) 7.33

Answer: Option ''

Solution is
Given

Average of first 17 natural numbers= (n + 1 ) / 2 
=(18 / 2 )
= 9
Average of first 17 multiples of 3 =(Average of first 17 natural numbers) x 3
= 9 x 3

203.

In a class of 37, the overall weight of the students is 743. Can you find the average weight of students in the class?

   A.) 19.08
   B.) 20.08
   C.) 22.09
   D.) 21.08

Answer: Option 'B'

Use the below formula to find the average weight of the class Average Weight = ( Total Weight of Class / Total Number of Students) Average Weight = ( 743/37) = 20.08

204.

Find the average of the first 56 natural numbers 

   A.) 28
   B.) 28.5
   C.) 29
   D.) 29.5

Answer: Option 'B'

Solution is
Average of n natural numbers = (n + 1) / 2
= (56 + 1) / 2
= 57 / 2
= 28.5
Answer is 28.5

205.

The average weight of a class having 16 students is 36 kg. Find the total weight of the class.

   A.) 576
   B.) 556
   C.) 496
   D.) 526

Answer: Option 'A'

Solution is
Given :
Average weight of a class having 16 students is 36 kg
Average = Total Quantity / No. of Quantity
Total quantity = Avg x No. of Quantity

Total quantity = 16 x 36 = 576
Answer is 576

206.

In the first 10 overs of a cricket game, the run rate was only 7.6. What should be the run rate in the remaining 40 overs to reach the target of 212 runs?

   A.) 3.8
   B.) 3.4
   C.) 4.8
   D.) 7.4

Answer: Option 'B'

Given
First 10 overs in a cricket game
Run rate = 7.6
Required run rate in the remaining 40 overs to reach the target of 212 runs
Required Run rate
= ( 212 - ( 7.6 x 10 ) ) / (40)
= ( 136) / (40)
= 3.4.

207.

 In a class of 18 students in an examination in science 1 student scored 100 marks, 2 get zero each and the average oh the rest was 45. What is the average of the whole class? 

   A.) 41
   B.) 43
   C.) 42
   D.) 44

Answer: Option 'B'

43

208.

A man covered a certain distance at a speed of 8 Kmph and returned at a speed of 4 Kmph. Find the average speed of whole journey? 

   A.) 3 ¾ Kmph
   B.) 5 1/3 Kmph
   C.) 4 ¼ Kmph
   D.) 2 ¼ Kmph

Answer: Option 'B'

5 1/3 Kmph

209.

There were 8 students in a particular Class. The class teacher knows the overall height of all the students in the class is 1300. Can you find the average height of students in the class?

   A.) 154.38
   B.) 162.5
   C.) 170.63
   D.) 178.75

Answer: Option 'B'

Use the below formula to find the average height of students in the class Average Height
= ( Total Height of all students in the Class / Total Number of Students) Average Height = ( 1300/8) = 162.5

210.

In the first 35 overs of a cricket game, the run rate was only 6.4. What should be the run rate in the remaining 15 overs to reach the target of 410 runs?

   A.) 12.4
   B.) 13.4
   C.) 15.25
   D.) 17.25

Answer: Option 'A'

Required Run rate = ( 410 - ( 6.4 x 35 ) )/ (15) 
= ( 186) /(15) = 12.4

211.

In the first 30 overs of a cricket game, the run rate was only 7. What should be the run rate in the remaining 20 overs to reach the target of 325 runs. ?

   A.) 7.75
   B.) 5.15
   C.) 6.75
   D.) 5.75

Answer: Option 'D'

Required Run rate = ( 325 - ( 7 x 30 ) )/ (20) = ( 115) /(20) = 5.75

212.

The average of 5 consecutive numbers is n. if the next two number are also included. The average will? 

   A.) Remain the same
   B.) Increase by 1
   C.) Increase by 2
   D.) Decrease by 1

Answer: Option 'B'

Increase by 1

213.

Six years ago the average of a family of 4 members was 26 years. A child has been born, due to Which the average age of the family is 24 years today. What is present age of the child? 

   A.) 4years
   B.) 6years
   C.) 8years
   D.) 5years

Answer: Option 'C'

8 years

214.

The average of 14 numbers is zero. Of them, at the most how many may be greater than zero ?

   A.) 14
   B.) 13
   C.) 12
   D.) 7

Answer: Option 'B'

Average of 14 numbers is = 0
Therefore sum of all 14 numbers = 0
It is quite possible that 13 of these numbers may be positive and if their sum is "a" then 14th number is "(-a)"

215.

The average weight of a class having 14 students is 44 kg. Find the total weight of the class.

   A.) 606
   B.) 616
   C.) 626
   D.) 636

Answer: Option 'B'

Solution is
Given, average weight = 44 kg.
No. of students = 14
Average = Total Quantity / No. of Quantity
=> Total quantity = Avg x No. of Quantity
=> Total weight of the class = Average weight x No. of students
= 44 x 14
= 616

216.

In a class of 19, the overall weight of the students is 1024. Can you find the average weight of students in the class?

   A.) 53.89
   B.) 56.58
   C.) 51.2
   D.) 59.28

Answer: Option 'A'

Use the below formula to find the average weight of the class
Average Weight = (Total Weight of Class / Total Number of Students)
Average Weight = (1024/19) = 53.89

217.

Sachin is younger than Rahul by 7 years. If their ages are in the respective ratio of 7 : 9, how old is Sachin? 

   A.) 16 years
   B.) 18 years
   C.) 24.5 years
   D.) 28 years

Answer: Option 'C'

Given
Let Rahul's age be x years.
Then, Sachin's age = (x - 7) years.
Therefore, x - 7 / x = 7/9
=> 9x - 63 = 7x => 2x = 63
=> x = 31.5
Hence, Sachin's age =(x - 7) = 24.5 years.

218.

The average of 12 numbers is 24. If each number be multiplied by 6. Find the average of new set of numbers?

   A.) 48
   B.) 144
   C.) 65
   D.) 121

Answer: Option 'B'

New Average = Old Average x 6 = 24 x 6 = 144

219.

The average of 10 numbers is 25. The average of first three numbers is 22 1/3 and that of next five is 15 1/5. If the eighth be less than the ninth and tenth numbers by 5 and 11 respectively, then the tenth number is:

   A.) 29
   B.) 21
   C.) 41
   D.) 30

Answer: Option 'C'

41

220.

In the first 30 overs of a cricket game, the run rate was only 6.4. What should be the run rate in the remaining 20 overs to reach the target of 225 runs?

   A.) 1.7
   B.) 2
   C.) 1.5
   D.) 2.9

Answer: Option 'A'

Required Run rate = ( 225 - ( 6.4 x 30 ) )/ (20) = ( 33) /(20) = 1.65


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