The Normal distributionAQA A-Level Maths: Mind map

Exam questions on The Normal distribution

1. The mass of eggs from a farm is modelled by the random variable $X\sim N(60,4^2)$, where $X$ is measured in grams.
   Eggs with a mass between $56$ g and $63$ g are classed as medium. Find the probability that an egg chosen at random is medium.2 marks
2. The time $T$ minutes that students take to complete a puzzle is modelled by the Normal distribution with mean $25$ and standard deviation $6$.
   Find the interquartile range of $T$.2 marks
3. A nursery models the height $Y$ cm of its two-year-old saplings as $Y\sim N(\mu,\sigma^2)$. It is found that $20\%$ of saplings are shorter than $30$ cm and $10\%$ of saplings are taller than $45$ cm.
   Find the values of $\mu$ and $\sigma$.3 marks