## FPSC, PPSC, NTS, OTS, STS, PTS, Mathematics, Average, Ratio, Percentage, related Test Preparation Material.

**Average **

**1) Height of 10 students in a certain class is 155 cm, 158 cm, 162 cm, 160 cm, 165 cm, 165 cm, 156 cm, 166 cm, 164 cm and 169 cm. What is average height of a student in the class.**

(A) 158 cm

__(B) 162 cm__

(C) 166 cm

(D) 164 cm

**Solution:
**Average =

**Sum/total number**

Total height of students = (155 + 158 + 162 + 160 + 165 + 165 + 156 + 166 + 164 + 169)

= 1620

= **1620/10**

= 162

**2) Alex buy three books for Rs. 16 each and four books for Rs. 23 each. What will be the average price of books.**

(A) 16

(B) 24

(C) 18

(__D) 20__

**Solution:
**Price of 3 books = 16*3 = 48

Price of 4 books = 23*4 = 92

48+92 = 140

140/7

= 20

**3) The average weight of a class of 13 students is 14 kg. When two more students joined the class, the average rose by 3 kg. What is the average weight of the two new students**

(A) 72

(B) 66

__(C) 36.5__

(D) 68

**Solution:
**Weight of 13 students => 13*14 = 182

New weight of students when 2 more students joined the class 15*17 = 255

Difference in weight = 255-182 = 73

Sum of the weights of the two new students =73.

Average of two new students =

**73/2**

= 36.5

**4) The average of 8 numbers is 12. If each number is increased by 2, the average of the new set of numbers is:**

__(A) 14__

(B) 13

(C) 12

(D) 15

**Solution:
**If the average of 8 numbers is 12, their sum must be 96.

Increasing each number by 2, new sum must be 96 + 16 = 112

So, new average is =

**112/8**

= 14

**5) Average of all prime numbers between 30 to 50 is?**

(A) 36

(B) 37.5

(C) 37

__(D) 39.8__

**Solution:
**Prime numbers between 30 and 50 are:

31, 37, 41, 43, 47

Average of prime numbers between 30 to 50 will be

**= 31 + 37 + 41 + 43 + 47 / 5**

= **199/5**

= 39.8

**6) Average salary of all the employees in a factory is Rs. 600. The average salary of the officers is Rs. 4000 and that of the rest of the workers is Rs. 560. If there are 12 officers, the total number of workers in the factory are?**

(A) 1006

(B) 1024

__(C) 1020__

(D) 1030

**Solution:
**Total officers salary + Total workers salary = Net salary of all employees

12 * 4000 + x * 560 = 600(x + 12)

48,000 + 560x = 600x + 7200

48,000 – 7200 = 600x – 560x

40,800 = 40x

=

**40,800/40**

= 1020