# Normal Distribution: Probability Example

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.

A-level Statistics: Normal Distribution, P(X less than x)
We show you through an example how to work out probabilities from a normal distribution.

Example:
A battery has a lifetime which is 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?

A-level Statistics: Normal Distribution, P(X more than x)

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

Normal Distribution: P(more than x) where x is less than the mean
In this tutorial we show you how to calculate the probability given that x is less than the mean from a normal distribution by looking at the following example.

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

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