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## 'Litov's Mean Value Theorem' printed from http://nrich.maths.org/

Start with two numbers, say 8 and 2.
Let's generate a sequence where the next number is the mean of the previous two numbers.

So the next number is half of $(8 + 2)$, and the sequence continues: $8, 2, 5$

The next number is half of $(2 + 5)$, and the sequence continues: $8, 2, 5, 3.5$

**What would happen if you continued this process indefinitely?**
Choose a few pairs of starting numbers and repeat the process.

Each time, your sequence should get closer and closer to a value which we call the

*limit*.

**Can you find a relationship between your starting numbers and the limit of the sequence they generate?**
Can you explain why this happens?

Now start with three numbers.

This time, we can generate a sequence where the next number is the mean of the last three numbers.

Check you agree that if we start with $4, 1, 10$, the next number is 5, and the number after that is $\frac{16}{3}$.

**What would happen if you continued this process indefinitely?**
Choose some more sets of three starting numbers.

**Can you find a relationship between your starting numbers and the limit of the sequence they generate?**
Can you explain why this happens?

Extension

Explore what happens when you have $n$ starting numbers and you generate a sequence where the next number is the mean of the last $n$ numbers.