(a)
We have five pulse rates randomly selected with a mean of 74.4 beats per minute. We have four pulse rates given. We let x be the value of the fifth pulse rate. We have n equals 5 here since we have sample space of 5. We illustrate the mean of the pulse rates as
[tex]\begin{gathered} \operatorname{mean}=\frac{\sum x}{n} \\ \\ 74.4=\frac{84+66+79+57+x}{5} \end{gathered}[/tex]Let's solve for the value of x. We have
[tex]\begin{gathered} 74.4=\frac{286+x}{5} \\ 286+x=(74.4)\cdot5 \\ 286+x=372 \\ x=372-286 \\ x=86 \end{gathered}[/tex]Hence, the missing value is equal to 86.
Answer: 86
(b) The number of degrees of freedom is calculated using the equation
[tex]\text{Degrees of freedom}=n-1[/tex]We already identified that the sample space n is equal to 5. Hence, the degrees of freedom is equal to
[tex]\text{Degrees of freedom}=5-1=4[/tex]Answer: 4
