一道英文统计题

题目

一道英文统计题
a box contains 10 tickets.each ticket is marked with a whole number between -5 and 5.The numbers are not all the same;their average equals 0.
(a) 100 draws are made from the box,and you win $1 if the sum is between -15 and 15
(B) 100 draws are made from the box,and you win $1 if the sum is between -30 and 30
以上两种选择应该选哪个获利多?为什么?

答案