வெல்லுங்கள் CSAT 2025 - 8: Q&A on Average

Questions & Answers (Multiple Choice) - Average
கொள்குறி வினா- விடைகள் - சராசரி

1. In a family of 6 members average monthly salary is ₹ 24000. If the annual salary of the eldest member increased by ₹ 72000, What will be the new average monthly salary of the same six members?
a. ₹36000 b. ₹25000
c. ₹30000 d. ₹27000

2. The captain of a cricket team of 11 players is 25 years and the wicket keeper is 5 years older. If the ages of these two players are excluded, the average age of the remaining players is one year less than the average of the whole team. Find the average age of the whole team.
a. 25 years b. 24 years
c. 23 years d. 22 years

3. A Planetarium has an average of 658 visitors on Sundays and 410 visitors on other days during March 2025. Find the average number of visitors per day in the month of March 2025 beginning with Saturday.
a. 450 b. 470 c. 480 d. 510

4. The average age of P and R is 43 years and that of Q and R is 40 years.
If the average age of P, Q and R is 45 years, then the age of R is
a. 41 b. 37 c. 40 d. 31

5. The average age of husband, wife and child 4 years ago was 28 years and that of wife and child after 5 years would be 29 years. What is the present age of husband? (in years)
a. 45 b. 47 c. 48 d. 51

6. In Rahul's opinion, his weight is greater than 67kg but less than 74kg. Raj, his brother says that Rahul's weight is greater than 62kg but less than 72kg. Rahul's sister's view is that his weight cannot be greater than 70kg. If all of them are correct in their estimation, what is the average of different probable weights of Rahul?
a. 68 b. 69 c. 70 d. 71

7. The average height of two-thirds of boys in the class is 60.6cm and that of the rest of the boys is 59.7cm. Find the average weight of all the boys in the class.(in cm.)
a. 60 b. 60.1 c. 60.2 d. 60.3

8. A student's marks were wrongly entered as 75 instead of 57. Due to that the average marks of the class got increased by (1/2). The number of students in the class is
a. 36 b.18 c. 42 d. 24

9. A motorist drove from the place P to Q at a speed of 60km/ph. After finishing his work, the tired motorist returns back to from Q to P at a speed of 40km/ph.
What is his average speed in km/ph of the motorist of both journeys?
a. 52 b. 50 c. 48 d. 55

10. The average of 9 consecutive positive integers is 'n'. If the next two integers are included, then the average of 11 numbers is
a. 'n' b. 'n+1' c. 'n+2' d. 'n+3'

11. The average weight of three men A, B and C is 74kg. Another man D joins the group the average becomes 72kg. If another man E, Whose weight is 4kg more than D replaces A, then the average weight of B, C, D and E becomes 71kg. The weight of A is
a. 71kg b. 72kg c. 73kg d. 74kg

12. The average score of marks secured in English by first ten students in the class of 19 students is 64 and that of last ten students is 70. If overall average marks of English of the class is 68, find the mark of the tenth student.
a. 68 b. 66 c. 48 d. 56

13. In a cricket match between India and England. After winning toss, India took batting first and scored 311 runs in the stipulated 50 overs match. On chase, England's run rate after 20 overs is 3.6.
What will be the run rate to win the match by England in the remaining 30 overs?
a. 8 b. 7.2 c. 7.9 d.8.2

14. What is the average of all prime numbers between 60 and 100?
a. 79 b. 77.5 c. 78 d.80.5

15. If the alphabets are assigned to numbers from 1 to 26 according to its positions from the left. If all the vowels are removed, then what is the average of sum of numbers asigned to all the consonants? (Corrected to one decimal)
a. 13.1 b. 13.5 c. 14.1 d. 14.3

Answers

1. b 2. c 3. a. 4. d 5. c

6. b 7. d 8. a 9. c 10. b

11. d 12. c 13. a 14. b 15. d

Explanation to Answers

1. New average = 24000 + (72000/12)÷6
= 24000 + 1000 = 25000
Hence the new average monthly salary of the same six members is ₹ 25000.

2. Let the average age of the whole team be 'x' years.
So 11x = 25 + 30 + 9(x - 1)
-> 2x = 46 -> x = 23
Hence the average age of the whole team is = 23 years.

3. Since the month starts on Saturday, there will be 5 Sundays in March 2025.
By problem
Required average
= (5×658 +26×410)/(31) = (3290+10660)/31 = 13950/31 = 450

4. The total age of three persons is
P + Q + R = 45×3 = 135
But P + R = 43×2 = 86
And Q + R = 40×2 = 80
Here P + Q + 2R = 86 + 80 = 166
Hence R's age = 166 - 135 = 31 years.

5. Sum of the present ages of husband, wife and child is (28×3 + 4×3) = 96
Sum of the present ages of wife and child is = 29×2 - 5×2 = 48 years
Husband's present age = 96 - 48 =48 yrs.

6. Let W be the weight of Rahul
According to Rahul, 67 < W < 74
According to Raj, 62 < W < 72
According to his Sister, W < 70 or = 70
The probable values of W satisfying all the conditions are 68, 69 and 70.
Hence the average is
(68 + 69 + 70)/3 = 69.

7. Here
[(2/3)×60.6 + (1/3)×59.7] ÷ (2/3+1/3)
= 40.4 + 19.9 = 60.3

8. Let the number of students be 't'
Total increase in marks = (t ×1/2) = (t/2).
Here t/2 = 75 - 57 = 18 -> t ,= 36.

9. Let the speed of the motorist from P to Q and Q to P be 'x' and 'y' respectively.
Then the average speed is
{2xy/(x+y)}.
If 'd' be the distance between P and Q,
Then the total distance covered is '2d'
The total time taken = (d/x) + (d/y)
Average speed = (2d)/{(d/x) + (d/y)}
= {2xy/(x+y)}
Here (2×60×40)÷(60+40) = 48km/ph

10. Here the middle number of 9 consecutive positive integers is 'n'
So first number is 'n-4' and nineth number is 'n+4'. So 10th and 11th numbers are 'n+5' and 'n+6'
Therefore the sum of 11 numbers exceeds '11n' by 5+6 = 11.
i.e., the average exceeds 'n' by 1.
Hence the new average is 'n+1'.

11. The total weight of A, B and C is
3×74 = 222; After D joins the group the total weights of A, B, C and D is
4×72 = 288 ; Here D's weight
= 288 - 222 = 66 ; And E's weight
66+4 = 70;
The total weights of B, C, D and E is
4×71= 284 ;
The sum of weights of B and C is
= 284 - (66+70) = 148
The weights of A = (The total weight of A, B and C) - (sum of weights of B and C)
= 222 - 148 = 74kg.

12. Marks scored by tenth student
= 68 + 10(64-68) + 10(70-68)
= 68 -40 +20 = 48

13. To win the match England should make the score target 312.
After 20 overs, the score is 20×3.6 = 72
The runs to score in 30 overs
= 312 - 72 = 240
Required run rate is = (240)/(30) = 8

14. The prime numbers between 60 and 100 are 61, 67, 71, 73 ,79, 83, 89 and 97
Sum = 61+67+71+73+79+83+89+97
= 620
Required average = 620/8 = 155/2 = 77.5

15. The numbers assigned to vowels
are 1, 5, 9, 15 and 21
Sum of numbers of all alphapets
= (26×27)/2 = 351
Sum of numbers of all vowels
= 1+5+9+15+21 =51
So sum of numbers of consonants
= 351 - 51 = 300
Hence the required average is
300/21 = 100/7 = 14.3

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