Average Questions for RRB NTPC set-2 PDF
Download RRB NTPC Average Questions PDF. Top 15 RRB NTPC questions based on asked questions in previous exam papers very important for the Railway NTPC exam.
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Question 1: The average marks obtained by a group of 16 students was 20. One student left the group as a result of which the average of the remaining students rose to 21. But another student joined,as a result of which the average marks of the group dropped a bit and became 20.5. What was the average marks obtained by the student who left and the one who joined?
a) 10
b) 11
c) 8
d) 9
Question 2: Mean temperature of a city for a week is $28^\circ$C. If the mean temperature for Monday, Tuesday, Wednesday and Thursday is $27.5^\circ$C and the mean temperature for Thursday, Friday, Saturday and Sunday is $29^\circ$C, the temperature recorded for Thursday is
a) $ 30^\circ $
b) $ 29^\circ $
c) $ 31^\circ $
d) $ 28^\circ $
Question 3: In a class when test is conducted, mean of 25 students marks is 60. If mean of first 13 students marks is 70 and mean of last 13 students marks is 50 find the marks of the middle student when arranged in the ascending order.
a) 70
b) 40
c) 50
d) 60
Question 4: One-fourth of a certain journey was covered at an average speed of 45 km/hour, one third at the speed of 48 km/hour and the remaining journey at the speed of 50 km/hour. The average speed of the whole journey in km/hour is:
a) 54
b) 51
c) 48
d) 46
Question 5: The average age of 8 persons in a committee is increased by 2 years when two men whose gases are 35 years and 45 years are replaced by two women. The average age of two women is (in years)
a) 40
b) 42
c) 48
d) 45
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Question 6: Of the three numbers whose average is 60, the first is one fourth of the sum of the others, The first number is
a) 30
b) 36
c) 42
d) 45
Question 7: The average expenditure of a man for the first five months is Rs. 1200 and for the next seven months is Rs. 1300. Find his monthly average income if he saves Rs. 2900 during the year ?
a) Rs. 1500
b) Rs. 1475
c) RS. 1450
d) Rs. 1425
Question 8: A bazar has an average of 510 people on sundays and 240 on other days. The average number of people per day in month of 30 days beginning with a sunday is:
a) 250
b) 276
c) 280
d) 285
Question 9: A labourer was engaged for 25 days on the condition that for every day, he works, he will be paid Rs. 2 and for every day, he is absent he will be fined 50p. If he receives only Rs. 37.50, find the no. of days he was absent-
a) 5
b) 6
c) 7
d) 4
Question 10: The average of age of father and mother is 45 years. If the age of daughter is included. The average of the three falls to 35. Find the age of daughter ?
a) 15
b) 10
c) 5
d) 20
Question 11: The average score of three boys in Mathematics is 30. When the score of a fourth boy is added to the total score of the three boys, the average is lowered to 25, What is the score of the fourth boy ?
a) 10
b) 15
c) 20
d) 25
Question 12: The average age of 8 persons in a committee is increased by two years when two men whose ages are 35 years and 45 years are replaced by two women. The average age of two women is (in yrs)–
a) 40
b) 42
c) 48
d) 45
Question 13: In a circle team of eleven players, one player weighing 42 kg, is injured and his place is taken by another player. If the average weight of the team is increased by 100 grams as a result of this, then the weight of the new player is–
a) 43.1 kg
b) 43.01 kg
c) 43.50 kg
d) 42.9 kg
Question 14: Of the three numbers, second is twice the first and is also thrice the third. If the average of the three numbers is 44, the largest number is-
a) 24
b) 72
c) 36
d) 108
Question 15: The average height of 35 students in a class is 4’2”. Three students of average height moved to new section while 6 students of total height 33’4” joined the class The average height of the student in the class is now
a) 4’6”
b) 5’
c) 4’4”
d) 4’8”
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Answers & Solutions:
1) Answer (D)
Total marks obtained by all the 16 students = 16*20 = 320
Now, 1 student left.
Marks obtained by 15 students = 15*21 = 315
Hence, Marks obtained by the student who left = 320-315 = 5 marks
Now, 1 student joined.
Marks obtained by 16 students = 16*20.5 = 328
Hence, Marks obtained by newly joined student = 328-315 = 13 marks.
Therefore, Required average = $\dfrac{5+13}{2} = \dfrac{18}{2} = 9$
2) Answer (A)
Given,
Mean temperature of a week = $ 28^{0} $ i.e Total temperature 28 x 7 = 196
Mean temperature for Monday, Tuesday, Wednesday and Thursday is $ 27.5^{0}$ i.e total temperature = 27.5 x 4 = 110 and
The mean temperature for Thursday, Friday, Saturday and Sunday is $ 29^{0}$ i.e total temperature = 29 x 4 = 116
Now, the temperature recorded for Thursday is,
(110 + 116) – 196 = 226 – 196 = 30
Hence, option A is the correct answer.
3) Answer (D)
According to the question,
Total marks obtained by all the students in the class = 25 x 60 = 1500
Total marks obtained by first 13 students = 13 x 70 = 910
Total marks obtained by last 13 students = 13 x 50 = 650
Marks obtained by the middle student(13th student) = (910 + 650) – 1500
= 1560 – 1500 = 60
Marks obtained by middle student = 60
Hence, option D is the correct answer.
4) Answer (C)
Let the total distance be 1200 kms
Time taken for first one fourth = 300/ 45 = 20/3 = 6.67
Next one third time = 400/ 48 = 25/3 = 8.33
Remaining = 500/50 = 10
Average speed = total distance / total time = 1200/25 = 48 kmph
5) Answer (C)
Let the average age of the women be A years.
Total of their ages = 2A
Total of the eight persons = ET
When replaced (ET – 80 + 2A)/8 = ET/8 + 2
2A – 80 = 16
A = 96/2 = 48
6) Answer (B)
The average of the three numbers is 60
The first number is one fourths of the sum of the others.
or 4p = q + r
$ \frac {p + q + r}{3}$ = 60
So, 5p/3 = 60
p = 180/5 = 36
7) Answer (A)
Let his monthly salary be x rupees.
So, 5 (x – 1200) + 7 (x-1300) = 2900
12x – 6000 – 9100 = 2900
So, x = 18000/12 = 1500
8) Answer (D)
There are 5 Sundays in the month that starts with sunday and 25 other days. So, the average =$ \frac{ 5 * 510 + 25 * 240}{30}$ = 285
9) Answer (A)
Let the employee be absent for x days.
He is present for 25 – x days.
His salary is (25 – x)*2 – .5x = 50 – 2.5x
But 50 – 2.5x = 37.5
So, x = 5
10) Answer (A)
Given,
(f+m)/2=45
=>f+m=90……(1)
Similarly, f+m+d=105……(2)
Subracting (2) from (1) we get,
d=15
11) Answer (A)
Sum of scores of the 3 boys=avg of scores of the 3 boys×no of boys=30×3=90
Sum of scores including the 4th boy=25×4=100
Thus, the score of the 4th boy=100-90=10
12) Answer (C)
Let the average age of the women be A years.
Total of their ages = 2A
Total of the eight persons = ET
When replaced (ET – 80 + 2A)/8 = ET/8 + 2
2A – 80 = 16
A = 96/2 = 48
13) Answer (A)
Let the weight of the new player be x kgs.
Total weight as a result of his inclusion = TW – 42 + x
Average weight = (TW – 42 + x)/11
But average weight before = TW/11
(TW – 42 + x)/11 – TW/11 = .1
x – 42 = 1.1
So, x = 43.1 kgs
14) Answer (B)
Let the first number be 3x. Second number is 6x. Third number is 2x.
So average = (2x + 3x + 6x)/3 = 11x/3
But 11x/3 = 44
So, x = 12
6x = 72
15) Answer (C)
After the students left, there will be 32 students with the same average height. 4 ft and 2 inches
Total height = 32 x 4.17 = 133.44
Total height of 6 students is 33 ft and 4 inches. = 33.33
New total height = 133.44 + 33.33 = 166.77
New average height = 166.77/ 38 = 4 feet 4 inches
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