[求助]GWD6-9

bobiouou

Q9:If an integer n is to be chosen at random from the integers 1 to 96, inclusive, what is the probability that n(n + 1)(n + 2) will be divisible by 8?

答案是5/8，可是能被8除的n应该是偶数，1~96一共有一半是偶数，所以是1/2。请教大家我算的对不对？

我是魔鬼

you have to consider this.. n(n + 1)(n + 2)

so if n = 7, 7 (8) (9) is divisible by 8

besides even numbers, you need to count all the odd numbers right before a 8 mulitple

so total even numbers 38 + 12 (those odd number) = 60

60/96 is the answer