Well, the probabilities add up to 1 and the first couple are correct so I'll give them a provisional tick. And I suppose you correctly entered the sum into a calculator (since you didn't keep a common denominator of 64) so I'll give the answer a provisional tick.

However, someone much more diligent than me and with way too much time on their hands might check it more thoroughly and, perhaps, disagree with me.

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1. There are two things you should never try to prove ...... the impossible and the obvious.

2. If you always do what you've always done, you'll always get what you've always got.

3. Lack of planning on your part does not constitute an emergency on my part.

4. Pressure makes diamonds.