Arithmetic Mcqs - Set 9

1)   The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is___________?

a. 17 kg
b. 20 kg
c. 26 kg
d. 31 kg
Answer  Explanation 

ANSWER: 31 kg

Explanation:
Let A, B, C represent their respective weights.

Then, we have:
A + B + C = (45 * 3) = 135 — (i)
A + B = (40 * 2) = 80 — (ii)
B + C = (43 * 2) = 86 — (iii)
Adding (ii) and (iii), we get: A + 2B + C = 166 — (iv)
Subtracting (i) from (iv), we get: B = 31
B’s weight = 31 kg

2)   The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is____________?

a. Rs. 3500
b. Rs. 4000
c. Rs. 4050
d. Rs. 5000
Answer  Explanation 

ANSWER: Rs. 4000

Explanation:
Let P, Q and R represent their respective monthly incomes. Then, we have:

P + Q = (5050 * 2) = 10100 — (i)
Q + R = (6250 * 2) = 12500 — (ii)
P + R = (5200 * 2) = 10400 — (iii)
Adding (i), (ii) and (iii), we get:
2(P + Q + R) = 33000 = P + Q + R = 16500 — (iv)
Subtracting (ii) from (iv), we get, P = 4000.
P’s monthly income = Rs. 4000

3)   The average monthly salary of 20 employees in an organisation is Rs. 1500. If the manager’s salary is added, then the average salary increases by Rs. 100. What is the manager’s monthly salary?

a. Rs. 2000
b. Rs. 2400
c. Rs. 3600
d. Rs. 4800
Answer  Explanation 

ANSWER: Rs. 3600

Explanation:
Manager’s monthly salary

= Rs. (1600 * 21 – 1500 * 20) = Rs. 3600

4)   The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. What is the average of the team?

a. 23 years
b. 24 years
c. 25 years
d. None of these
Answer  Explanation 

ANSWER: 23 years

Explanation:
Let the average of the whole team be x years.

11x – (26 + 29) = 9(x – 1)
= 11x – 9x = 46
= 2x = 46 => x = 23
So, average age of the team is 23 years

5)   A cricketer has a certain average for 10 innings. In the eleventh inning, he scored 108 runs, there by increasing his average by 6 runs. His new average is_____________?

a. 48 runs
b. 52 runs
c. 55 runs
d. 60 runs
Answer  Explanation 

ANSWER: 48 runs

Explanation:
Let average for 10 innings be x. Then,

(10x + 108)/11 = x + 6
= 11x + 66 = 10x + 108
= x = 42.
New average = (x + 6) = 48 runs

6)   The average age of a husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. The present age of the husband is___________?

a. 19 years
b. 23 years
c. 28.5 years
d. 29.3 years
Answer  Explanation 

ANSWER: 19 years

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

Required average = 57/3 = 19 years

7)   The arithmetic mean of the scores of a group of students in a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25% a mean score of 31. The mean score of remaining 55% is___________?

a. 45
b. 50
c. 51.4 approx.
d. 54.6 approx.
Answer  Explanation 

ANSWER: 51.4 approx.

Explanation:
Let the required means score be x. Then,

20 * 80 + 25 * 31 + 55 * x = 52 * 100
= 1600 + 775 + 55x = 5200
= 55x = 2825
= x = 565/11 = 51.4.

8)   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. 22
d. 23
Answer  Explanation 

ANSWER: 21

Explanation:
Let the total number of workers be x. Then,

8000x = (12000 * 7) + 6000(x – 7)
= 2000x = 42000
= x = 21

9)   In an examination a pupil’s average marks were 63 per paper. If he had obtained 20 more marks for his Geography paper and 2 more marks for his History paper, his average per paper would have been 65. How many papers were there in the examination?

a. 8
b. 9
c. 10
d. 11
Answer  Explanation 

ANSWER: 11

Explanation:
Let the number of papers be x. Then,

63x + 20 + 2 = 65x
= 2x = 22
= x = 11

10)   The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years. The ration of the number of boys to the number of girls in the class is___________?

a. 1:2
b. 2:3
c. 3:4
d. 3:5
Answer  Explanation 

ANSWER: 2:3

Explanation:
Let the ratio be k : 1. Then,

k * 16.4 + 1 * 15.4 = (k + 1) * 15.8
= (16.4 – 15.8)k = (15.8 – 15.4)
= k = 0.4/0.6 = 2/3
Required ratio = 2/3 : 1 = 2:3

11)   The average of women and child workers in a factory was 15%yr. The average age of all the 16 children was 8yr and average age of women workers was 22 yrs if ten women workers were married then the number of unmarried women workers were________?

a. 16
b. 12
c. 8
d. 6
Answer  Explanation 

ANSWER: 6

Explanation:
Let the number of women workers be x

According to the question 22*x+16*8 = 15(16+x)

=> 22x+128 =240 +15x

=> 22x-15x = 240 -128

=> 7x=112

Therefore, x=112/7 =16

Therefore, Unmarried women workers =(16-10) = 6

12)   The mean marks of 30 students in a class is 58.5. Later on it was found that 75 was wrongly recorded as 57. Find the correct them.

a. 57.4
b. 57.5
c. 58.9
d. 59.1
Answer  Explanation 

ANSWER: 59.1

Explanation:
Correct mean = 30x 58.5 -57 +75/30

= 1755+18/30 = 1773/30 = 59.1

13)   A person travels from x to y at a speed of 40Km/h and returns by increasing his speed 50%. What is his average speed for both the trips?

a. 36km/h
b. 45km/h
c. 48km/h
d. 50km/h
Answer  Explanation 

ANSWER: 48km/h

Explanation:
Speed of person from x to y =40 km/h

Speed of person from y to x =(40×150)/100 = 60km/h

Since the distance travelled is same

Therefore, Average Speed = (2x40x60)/40+60 = 48km/h

14)   The average of 18 observations was calculated and it was 124. Later on it was discovered that two observations 46 and 82 were incorrect. The correct values are 64 and 28. The correct average of 18 observations is___________?

a. 123
b. 137
c. 121
d. 122
Answer  Explanation 

ANSWER: 122

Explanation:
Sum of 18 observations = 18×124 =2232

Correct sum of 18 observations = 2232-46-82+64+28

= 2196

Therefore, Correct average =2196/18 = 122

15)   The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is___________?

a. 17 kg
b. 20 kg
c. 26 kg
d. 31 kg
Answer  Explanation 

ANSWER: 31 kg

Explanation:
Let A, B, C represent their respective weights. Then, we have: A + B + C = (45 x 3) = 135 …. (i) A + B = (40 x 2) = 80 …. (ii) B + C = (43 x 2) = 86 ….(iii) Adding (ii) and (iii), we get: A + 2B + C = 166 …. (iv) Subtracting (i) from (iv), we get : B = 31. B’s weight = 31 kg

16)   The average weight of 16 boys in a class is 50.25 kg and that of the remaining 8 boys is 45.15 kg. Find the average weights of all the boys in the class.

a. 47.55 kg
b. 48 kg
c. 48.55 kg
d. 49.25 kg
Answer  Explanation 

ANSWER: 48.55 kg

Explanation:
No explanation is available for this question!

17)   If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is__________?

a. 53.33
b. 54.68
c. 55
d. None of these
Answer  Explanation 

ANSWER: 54.68

Explanation:
Required average = (55 x 50 + 60 x 55 + 45 x 60) / (55 + 60 + 45)
= (2750 + 3300 + 2700) /160
= 54.68 is correct Answer

18)   Today is khadija’s birthday. After one year, she will become two times as she was ten years ago. current age of Khadija?

a. 19
b. 20
c. 21
d. 22
Answer  Explanation 

ANSWER: 21

Explanation:
let her age be x

after 1 year her age will be x+1=2(x-10)

x+1=2x-20

1+20=2x-x

x=21 years

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