Answer to Question #328051 in Statistics and Probability for Kpay

Question

The mean dying rate of mice administered yo a given dosage of an experimental drug is 45with a variance of 25. What is the probability randomly selected 55 mice, which received the drug, more than 50 will die? Assume normality

Answer 1

Let X=X= the number of mice that died:

$X∼N(μ,σ 2 )$

Given $\mu=45, \sigma^2=25$

$P(X>50)=1−P(X≤50) =1-P(Z\leq \dfrac{50-45}{\sqrt{25}})=1-P(Z\leq 1)=1−P(Z≤ 25 ​ 50−45 ​ )=1−P(Z≤1) \approx0.158655$