The average of the first 13 even natural numbers is:
14
Correct Answer: 14
First 13 even natural numbers: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26
Method 1 (Arithmetic Progression):
Sum = n/2 × (first + last) = 13/2 × (2 + 26) = 13/2 × 28 = 182
Average = 182/13 = 14
Method 2 (Shortcut): Average of first n even natural numbers = n + 1 = 13 + 1 = 14
Similar Questions
The average age of 23 students of a class is 25 years. If the age of the teacher is also included, the average age of the whole group becomes 26 years. The age (in years) of the teacher is:
For 6 innings, a cricketer had an average of 90 runs. In the 7th inning, he scored 157 runs. His average score increased by _______. (Round off the answer to the nearest whole number.)
Important Questions from Average
The average of 28 numbers is 77. The average of first 14 numbers is 74 and the average of last 15 numbers is 84. If the 14 th number is excluded, then what is the average of remaining numbers? (correct to one decimal places)
24 students collected money for donation. The average contribution was Rs. 50. Later on, their teacher also contributed some money. Now the average contribution is Rs. 56. The teacher’s contribution is:
Out of 6 numbers, the sum of the first 5 numbers is 7 times the 6 th number. If their average is 136, then the 6 th number is:
The average of five numbers is 30. If one number is excluded, then average becomes 31. What is the excluded number?
The average weight of 49 students in a class is 39 kg. Seven of them whose average weight is 40 kg leave the class and other seven students whose average weight is 54 kg join the class. What is the new average weight (in kg) of the class?
