91影视

The table given displays the number of females for each interval of blood platelet count.

There are five intervals of blood platelet count.

The actual value for standard deviation is 65.4.

For a grouped frequency distribution, thestandard deviation is computed using the following expression:

$s=\sqrt{\frac{n\left[鈭�\left(f脳x^2\right)\right]-{\left[鈭�\left(f脳x\right)\right]}^2}{n\left(n-1\right)}}$

Here,

• x defines the midpoints of the class intervals;
• n defines the total of all the frequencies.

The terms of the formula are computed as shown below:

Substituting the above values in the formula:

$$\begin{gathered} s=\sqrt{\frac{n\left[鈭�\left(f脳x^2\right)\right]-{\left[鈭�\left(f脳x\right)\right]}^2}{n\left(n-1\right)}} \\ =\sqrt{\frac{147\left(4264587\right)-{\left(22876.5\right)}^2}{147\left(147-1\right)}} \\ =69.5 \end{gathered}$$

Therefore, the calculated standard deviation is equal to69.5.

The actual value is 65.4.

The standard deviation value computed from the sample and the original list of values isapproximately equal to each other.