a, b, c, d, e, f, g are consecutive even numbers. j, k, l, m, n are consecutive odd numbers. The average of all the numbers is :

Answer: Option B

According to the question,
Consecutive even numbers
= a, b, c, d, e, f, g
Consecutive odd numbers
= j, k, l, m, n
Consecutive even numbers
2, 4, 6, 8, 10, 12, 14
$$\frac{2+4+6+8+10+12+14}{7}$$
= $$\frac{56}{7}$$
= 8 middle term
Consecutive odd numbers
1, 3, 5, 7, 9
$$\frac{1+3+5+7+9}{2}$$
= $$\frac{25}{5}$$
= 5 middle term
∴ Same as in above situation.
Average of even numbers = d
Average of odd numbers = 1
∴ Average of all numbers = $$\frac{1+d}{2}$$