请问这道数学题怎么解？

bni

One set of numbers consists of consecutive integers and the least number is 3. How many numbers are there in the set?

(1) The average of all the numbers in the set is 6;

(2) The number of integers is one more than the range of the set.

答案选A

bni

ArthurGoal 发表于 2018-9-23 05:39
A成立
因为是连续的 那d就是1，  集合只会是(3，4，5....An)
a1=3,  d=1,  n是位数

谢谢你！！！

ArthurGoal

A成立
因为是连续的 那d就是1，  集合只会是(3，4，5....An)
a1=3,  d=1,  n是位数
An=a1+(n-1)d=n+2
Sn=6n=(a1+An)*n/2    两边一算n=7     An=9      

B不成立
Range = An-a1=An-3=n-1  就和B的描述一摸一样，说不说都是废话
这个无法算出具体n是多少