(a(i))[4]
Determine the value of $\mu$.
(a(ii))[3]
Calculate $P(X < 4.7)$.
(b)[4]
Calculate the expected number of usable rods in a batch of $1000$ rods.
Mathematics 9709 · AS & A Level · Continuous random variables
Continuous random variables — practice question
Let $X$ be normally distributed with mean $\mu$ and standard deviation $\sigma$. It is known that $\sigma = 0.25\mu$ and that $P(X < 6.8) = 0.75$.