robotwrotedowninasheetofpapertheconsecutivenumbersstartingfrom1,2,3,.however,duetohiscareless,hedidn`twriteacertainnumber,andthisresultedtotheaverageofallthenumbersis178/13.Themissingnumberis

Question

robot wrote down in a sheet of paper the consecutive numbers starting from 1,2,3,.however,
due to his careless ,he didn`t write a certain number,and this resulted to the average of all the numbers is 178/13.The missing number is______

Answer 1

设有N个数,漏掉的数为X,
正常情况下,1,2,3.N,其平均值为(N+1)/2,X最大值为N,最小为1；
当X=N时,平均值为(N-1)/2；当X=1时,平均值接近于(N+1)/2；
当N＝26时,平均值为12.13.5,
当N＝27时,平均值为13～14,
当N＝28时,平均值为13.14.5,
由于,13.5