Q.1 Four years ago, the average age of four friends was 25 years. Now, with a fifth friend joining the group, their average is 24 years. What is the present age of the new friend?
A) 20 yrs
B) 21 yrs
C) 36 yrs
D) 24 yrs
Total age of all friends including new friend = 24 5 = 120 years
Present age of the new friend = new average age – old average age
120 – 100 = 20 years.
Q.2 Gavaskar’s average in his first 50 innings was 50. After the 51st innings, his average was 51. How many runs did he score in his 51st innings. (supposing that he lost his wicket in his 51st innings)
Explanation : Total score after 50 innings = 50*50 = 2500
Total score after 51 innings = 51*51 = 2601
So, runs made in the 51st innings = 2601-2500 = 101
If he had not lost his wicket in his 51st innings, he would have scored an unbeaten 50 in his 51st innings.
Q.3 In a class the average age is 16yrs.If the teacher who is 40 yrs of age is also included ,the average becomes 17yrs,how many students were there?
40 – 17 = 23 students
Q.4 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 ?
B) Rs. 16000
C) Rs. 16800
D) Can’t be determined
Increament = 5% of 16000
16000*5/100 = Rs. 800
Therefore incremented salary = 16000+800 = 16800
New salary after deducting transport allowance = 16800-800
Q.5 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 ?
No. of passed candidates
= Total Candidates (Total average – Failed average) / Passed average – Failed Average
Therefore, 120*(35-15) / 39-15