Melody

$$\\0.0081^{3/4}\\\\
=(0.0081^{1/4})^3\\\\
=0.3^3\\\\
=0.027$$

check

$${{\mathtt{0.008\: \!1}}}^{\left({\frac{{\mathtt{3}}}{{\mathtt{4}}}}\right)} = {\frac{{\mathtt{27}}}{{\mathtt{1\,000}}}} = {\mathtt{0.027}}$$

That was a great answer anon :)

The */ symbols together mean nothing so this cannot be calculated

I agree that the chance of getting all those letters in that order from any given starting point is 1/28^18   

I agree with how many letters are typed in a year.     

But after that you lost me.     

There is probably some key thing that I am supposed to understand but I do not understand.

In reality, the monkey could get that combination on the first go - it is afterall just as likely as any other set of 18 characters.  

OR

The monkey could type away for any finite period and the sentence will not appear.

I am sure that someone could work out the probability of it a appearing in any given period of time but I do no see how they could specify exactly how long it would take.

Like I said, I expect I am missing some key understanding of what is being asked here.  

What happened to my first possibility - it has disappeared :/

Here are other possibilities

You are welcome :)

I'll have a look and see if I can find something even better :)

$$\\0=1-6x\\
6x=1\\
x=1/6$$

This looks like it might be what you want 

Mmm

So you clock on at  8:23    and clock of at  6:18    and you want to know the easiest way to work out how many hours were worked.

Is that what you mean?