Practice questions to ace SI examinations

1. A grocer has a sale of Rs 6435, Rs 6927, Rs 6855, Rs 7230 and Rs 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs 6500? a) Rs. 4991 b) Rs.5991 c) Rs. 6001 d) Rs. 6991 Ans: a […]

1. A grocer has a sale of Rs 6435, Rs 6927, Rs 6855, Rs 7230 and Rs 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs 6500?

a) Rs. 4991 b) Rs.5991 c) Rs. 6001 d) Rs. 6991
Ans: a
Explanation:
Total sale for 5 months = Rs (6435 6927 6855 7230 6562) = Rs 34009.

Required sale = Rs [(6500 x 6) – 34009]

= Rs 39000 – 34009

= Rs 4991

2. 10 years ago, the average age of a family of 4 members was 24 years. Two children having been born (with age difference of 2 years), the present average age of the family is the same. The present age of the youngest child is :

a) 1 year b) 2 years c) 3 years d) 5 years

Ans: c

Explanation:

Total age of 4 members, 10 years ago = (24 × 4) = 96 years
Total age of 4 members now = (96 10 × 4) years = 136 years
Total age of 6 members now = (24 × 6) = 144 years
Sum of the ages of 2 children = (144 – 136) = 8 years
Let the age of the younger child be x years.
Then, age of the elder child = (x 2) years
So, x x 2 = 8
2x = 6
x = 3
So, age of younger child = 3 years
3. A Cinema hall usually sell 350 tickets in a day and Rs 13,12,500 is the April month income of that the Cinema hall get while selling the tickets. What is the average amount per person it gets?
a) 135 b) 125 c) 145 d) 356
Ans:b
Explanation:

350 tickets per day and April month has 30 days,
so total tickets in a month = 350 * 30 = 10500
Therefore average amount per persons is
13,12,500/10500 = 125
4. The average weight of 4 men is increased by 3kg when one of them whose weigh 60 kg is replaced by another man. What is the weight of the new man?

(a) 63 kg (b) 64 kg (c) 68 kg (d) 72 kg

Ans: d

Explanation:

If the average is increased by 3 kg, then sum of weights increases by = 3 × 4 = 12 kg.
And this increase in weight is due to the extra weight included due to the inclusion of new person.
Weight of new man = 60 12 = 72 kg.
5. The average salary per month of 30 employees in a company is Rs 4000. If the manager’s salary is added, the average salary increases to Rs 4300. What is the salary of the manager?
a) Rs 10,000 b) Rs 12,000 c) Rs 13,000 d) Rs 13,300
Ans: d
Explanation:
Salary of the manager = (31 × 4300 – 30 × 4000) = Rs 13,300.

6. The average age of 40 student of a class is 15 years. When 10 new students are admitted, the average is increased by 0.2 years. The average age of new students is

a) 15.2 yrs b) 16 yrs c) 16.2 yrs d) 16.4 yrs

Ans: b

Explanation:
Sum of ages of 10 new students = (50 ×15.2 – 40×15) = 160 years

Average age of new students = 160/10 = 16 years

7. 5 years ago, the average age of the family of 4 members was 28 years. A baby having been born, the average age of the family is the same today. The present age of the baby is in years?
a) 8 b) 7.5 c) 7 d) 8.5
Ans: a
Explanation:
Total age of the 4 members 5 years ago

Total age of 4 members now

Total age of 5 members now

Age of the baby =140-132=8 years

8. In an examination, a pupil’s average marks were 51 per paper. If he had obtained 15 more marks for his Botany paper and 6 more marks for his Biology paper, his average per paper would have been 54. How many papers were there in the examination?

a) 8 b) 9 c) 7 d) 11

Ans: c

Explanation:

Let the number of papers be X
Then,
51x 15 6 =54x
3x =21

x=7
9. There were 35 students in a hostel. If the number of students increases by 7, the expenses of the mess increase by Rs 42 per day while the average expenditure per head diminishes by Rs1. Find the original expenditure of the mess.
(a) Rs. 400 (b) Rs. 340 (c) Rs. 420 (d) Rs. 450
Ans: c
Explanation:
If 7 members join the mess, total expenditure = 35x 42

Now, the average expenditure = (35x 42)/ (35 7) = x – 1

35x 42 = 42x – 42

x = 12

Thus the original expenditure of the mess = 35 × 12 = Rs. 420

10. The average weight of 3 men A, B and C is 84 kg. Another man D joins the group and the average now becomes 80 kg. If another man E, whose weight is 3 kg more than that of D, replaces A then the average weight of B, C, D and E becomes 79 kg. The weight of A is

a) 70 kg b) 72 kg c) 75 kg d) 80 kg

Ans: c

Explanation:

A B C = (84×3) = 252kg,
A B C D= (80×4) = 320kg.
D = (320 – 252) = 68,
E = (68 3) =7l.
B C D E = (79×4) =316.
(A B C D) – (B C D E) = (320 – 316) kg = 4kg.
A – E = 4 = A = (4 E) = 75kg.