The average of four consecutive even numbers is 15. The 2nd highest number is:

16

No's. are :  12, 14, 16, 18 in which 15 lies exactly in the middle and also the average of all four numbers.

Therefore, 2nd highest no. is 16

Alternate solution:

Let the first even number be 2n;

Then ; required number can be written as 2n, 2n+2, 2n+4, 2n+6

Average = 15 ⇒ \(\frac{(2n)+(2n+2)+(2n+4)+(2n+6)}{4}\)

⇒ \(\frac{8n+12}{4}\) = 15 ⇒ 2n+3 = 5

2n = 12 or n = 6

2nd highest number = 2n + 4 = 16