Question

If in a binomial distribution mean is 5 and variance is 4, write the number of trials.

Answer 1

$$\begin{gathered} \mathrm{Mean}=5\mathrm{and}\mathrm{Variance}=4 \\ \Rightarrow np=5\mathrm{and}npq\mathit{}=4 \\ \Rightarrow q=0.8 \\ \Rightarrow p=1-q=0.2 \\ \&np\mathit{}=n(0.2)=5\left(\mathrm{given}\right) \\ \Rightarrow n=\frac{5}{0.2}=25 \end{gathered}$$