Q.1 A student on her first 3 tests received an average score of N points. If she exceeds her previous average score by 20 points on her fourth test, then what is the average score for the first 4 tests?

A) N + 20

B) N + 10

C) N + 4

D) N + 5

Ans. D

Required Average= 4N+20/4

= 4N/4 + 20/

= N+5

Q.2 If the weight of a group of 20 boys was calculated to be 89.4 kg& it was later discovered that one weight was misread as 78 kg instead of the correct one of 87 kg. Then the correct average weight (in kg ) is:

A) 89.25

B) 89.85

C) 88.95

D) 89.55

Ans. B

Total weight of 20 boys which is wrong = 89.4 * 20

= 1788 kg

Therefore, correct weight of 20 boys = 1788 – 78 + 87

= 1797 kg

Therefore, correct average weight = 1797 / 20 = 89.85 kg

Q.3 Average salary of 100 employees in an office is Rs.16000 /month. Management decided to raise salary of every employee by 5% but stopped a transport allowance of Rs. 800 /month which was paid earlier to every employee. What will be the average monthly salary ?

A) Rs.16500

B) Rs. 16000

C) Rs. 16800

D) Can’t be determined

Ans. B

Increament = 5% of 16000

16000*5/100 = Rs. 800

Therefore incremented salary = 16000+800 = 16800

New salary after deducting transport allowance = 16800-800 =Rs. 16000

Q.4 Average marks obtained by the 120 candidates in a certain exam is 35. If the average marks of the passed candidates is 39 & that of the failed candidates is 15. What is the no. of candidates passed the exams ?

A) 100

B) 200

C) 120

D) 220

Ans. A

Shortcut:

No. of passed candidates = Total Candidates (Total average – Failed average) / Passed average – Failed Average

Therefore, 120*(35-15) / 39-15

=100

Q.5 A man spends on an average Rs.450 for the first 8 months & Rs. 475 for the next 4 months. If he saves Rs.500. What is the monthly salary?

A) 300

B) 400

C) 500

D) 600

Ans. C

450*8 = 3600

475*4 = 1900

Therefore, total expenditure = Rs.500

But saving is : 500

Thus total salary is=6000

So, Monthly salary = 6000/2 = 500 Rs.