(i)[4]
Find both the mean and the standard deviation.
(ii)[5]
Find the probability that at least $160$ of these $200$ values are less than $5$.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
A variable with a normal distribution has its mean equal to four times its standard deviation. For a value selected at random, the probability that it is above $5$ is $0.15$.