The average of nine numbers is 50. The average of the first five numbers is 54 and that of the last three number is 52. Then, the sixth number is

• 34

• 24

• 44

• 39

The average of the first nine integral multiples of 3 is

• 12

• 15

• 18

• 21

The average age of 14 girls and their teacher's age is 15 yr. If the teacher's age is excluded, then the average reduces by 1. What is the teacher's age?

• 29 yr

• 35 yr

• 32 yr

• 30 yr

The arithmeic mean of the scores of a group of students ia 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

• 54.6%

• 45%

• 50%

• 51.4%

A cricket player after playing 10 tests scored 100 runs in the 11th test. As a result, the average of his runs is increased by 5. The present age of runs is

• 45

• 40

• 50

• 55

106.

What is the Arithmetic mean of the first n natural numbers?

• 

• 

• 2(n+1)

• 

The average weight of 15 oarsmen in a boat is increased by 1.6 kg when one of the crew who weighs 42 kg is replaced by a new man. Find the weight of the new man (in kg).

• 67

• 43

• 66

• 65

The average of 17 results is 60. If the average of first 9 results is 57 and that of the last 9 results is 65, then what will be the value of 9th result?

• 39

• 78

• 117

• 156

A batsman makes a score of 111 runs in the 10th match and thus increases his average runs per match by 5. What will be his average after the 10th match?

• 66

• 61

• 62

• 64

What is the sum of 11 terms of an arithmetic progression if the 4th term is 11 and the 7th term is -4?

• -75

• 55

• 11

• 100