# Normal Distribution: Probability in a given range

These lessons, with videos, examples, solutions and worksheets, are suitable for A Level Maths to help students learn how to work out a probability in a given range.

Share this page to Google Classroom

Normal distribution: Finding the P(X less than x) x less than mean
There are four tutorials in this series which show you how to work out a probability in a given range.

Example:
A light bulb has lifetimes which are distributed with a mean of 520 hours and a standard deviation of 6 hours. What is the probability of a light bulb lasting less than 511 hours?

Normal distribution: Finding the P(X less than x) x more than mean

Example:
A battery has lifetimes which are normally distributed with a mean of 62 hours and a standard deviation of 3 hours. What is the probability of a battery lasting less than 68 hours?

Normal distribution: Finding the P(X less than x) x less than mean

Example:
A carton of orange juice has a volume which is normally distributed with a mean of 120 ml and a standard deviation of 1.8 ml. Find the probability that the volume is more than 118 ml.

Normal distribution: Finding the P(X more than x) x more than mean

Example:
The mases of a well known brand of breakfast cereal are normally distributed with a mean of 250 g and a standard deviation of 4 g. Find the probability of a packet containing more than 254.4 g.

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.