91影视

The number of times a repeated event occurs per unit of time is known as frequency. It's also referred to as temporal frequency to distinguish it from spatial frequency, and ordinary frequency to distinguish it from angular frequency.

\({\rm{100(1 - \alpha )\% confidence interval}}\)

the mean is calculated using,

\(\left( {{\rm{\bar x - }}{{\rm{z}}_{{\rm{\alpha /2}}}}{\rm{ \times }}\frac{{\rm{\sigma }}}{{\sqrt {\rm{n}} }}{\rm{,\bar x + }}{{\rm{z}}_{{\rm{\alpha /2}}}}{\rm{ \times }}\frac{{\rm{\sigma }}}{{\sqrt {\rm{n}} }}} \right)\)

when it is known what the value\({{\rm{\sigma }}^{\rm{2}}}\)is.

So, because sample mean is the middle of the provided interval,

\(\begin{array}{c}\left( {{\rm{\bar x + }}{{\rm{z}}_{{\rm{\alpha /2}}}}{\rm{ \times }}\frac{{\rm{\sigma }}}{{\sqrt {\rm{n}} }}{\rm{ + \bar x - }}{{\rm{z}}_{{\rm{\alpha /2}}}}{\rm{ \times }}\frac{{\rm{\sigma }}}{{\sqrt {\rm{n}} }}} \right){\rm{/2 = }}\frac{{{\rm{2\bar x}}}}{{\rm{2}}}\\{\rm{ = \bar x}}{\rm{.}}\end{array}\)

As a result, the sample mean,

\(\begin{array}{c}{\rm{\bar x = }}\frac{{{\rm{114}}{\rm{.4 + 115}}{\rm{.6}}}}{{\rm{2}}}\\{\rm{ = 115}}\\{\rm{ = }}\frac{{{\rm{114}}{\rm{.1 + 115}}{\rm{.9}}}}{{\rm{2}}}\end{array}\)

Therefore, the value is \({\rm{115}}\).