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.

**Related Pages**

Normal Distribution

Standard Deviation

Theoretical vs. Experimental Probability

More Lessons On Probability

A Level Maths

Math Worksheets

**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
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