用FX-50 計算mean同standard deviation既問題 (急用)

An analysis of the register, for a random sample of 100 days, results in the following information on the number, X, of visitors per day

Number of visitors per day:
1-10, 11-20, 21-25, 26-30, 31-35, 36-40, 41-50, 51-100
Number of days:
13, 33, 17, 12, 8, 5, 5, 7


以上題為例子
請問要點樣用FX-50 黎計算出mean同standard deviation??
要用d咩模式, 禁d咩制同埋最後顯示出黎既答案係咩?

下個星期就考, 好急用架!! 唔該哂!