[求助]请教费费第六部分#7

colorsofthewin

7、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: A 请教思路......

susanoffice

最小的是3，设总共k个数，那么最大的就是3+k-1。平均数就是(3+3+k-1)/2 = 6，那么k=7。
2)其实我上面都已经推出来了，最大是3+k-1，那么range就是(3+k-1)-3 = k-1，所以2基本就是废话。答案就是A。

colorsofthewin

多谢啦, 很久没碰数学,脑子好象生锈啦. 我看的费费上的解释看也看不懂. 听你的一看就明白了, 原来它上面的解释公式写错了,搞得我一头雾水.