91影视

Probability of success $\left(p\right)=9\%=0.09$

Number of trials $\left(n\right)=15$

The mean and standard deviation are calculated using the following formula:

$Mean\left(渭\right)=n脳p$

Standard deviation $\left(蟽\right)=\sqrt{n脳p脳(1-p)}$

Assume X to be the random number of calls that aid in the completion of the survey, which follows the binomial distribution.

If more than 12 calls go unanswered, that suggests fewer than 3 calls were made.

The following formula can be used to compute the probability:

$$\begin{gathered} P(X<3)=P(X=0)+P(X=1)+P(X=2) \\ =\underset{r=0}{\overset{2}{鈭�}}{}^{15}C_r脳(0.09{)}^r脳(1-0.09{)}^{15-r} \\ =0.8531 \end{gathered}$$

Thus, the required probability is $0.8531$.

Given:

Probability of success $\left(p\right)=9\%=0.09$

Number of trials $\left(n\right)=15$

The mean of X can be computed using the formula:

$\begin{array}{rcl}{渭}_X& =& n脳p\\ & =& 15(0.09)\\ & =& 1.35\end{array}$

Therefore, the value of mean is 1.35

Given:

The Probability of success$\left(p\right)=9\%=0.09$

The number of trials $\left(n\right)=15$

X's standard deviation can be determined as follows:

$\begin{array}{rcl}{蟽}_X& =& \sqrt{n脳p脳(1-p)}\\ & =& \sqrt{15(0.09)(1-0.09)}\\ & =& 1.1084\end{array}$