The average of seven consecutive odd numbers (in increasing order) is k. If the next four consecutive odd numbers are included, then the average of all the numbers is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. k + 4.
Let the 7 consecutive odd numbers be: (k - 6), (k - 4), (k - 2), k, (k + 2), (k + 4), (k + 6)
Average = k
Next 4 odd numbers: (k + 8), (k + 10), (k + 12), (k + 14)
Sum of 7 numbers = 7 × k
Sum of next 4 = (k + 8) + (k + 10) + (k + 12) + (k + 14) = 4k + 44
Total sum = 7k + 4k + 44 = 11k + 44
Average = = k + 4