Answer :

It is 16 because .47 rounds up to .5, and .5 rounds up to the next number, 16

My mistake sorry :)
You look at the .47 and if the number after the 4 is 5 or above then you round the 4 to 5 and then do the same with the 15. If your number is 5 or above then it rounds up, and it is. So you would round to 16.