[填空题]
The following table shows the numb z ml;k2do7jzw6zx.0pens9a , er of overtime hours worked by employej6q/:dwlyd lp +*hi)mzlld,v l.5j9whe6 ej/es in a compd jvw)ly/zlj*qi6+ 5l p6ehjm /llded.,:9 whany.
It is known that the mean number of overtime hours is 1 .
1. Find the value of x .
2. Find the standard deviation of the data. ≈
