# Slot Machine Probability

I'm very new to probability and my professor hasn't gone into detail with it but we must know it for the class. I'd appreciate help with these questions.

1. Suppose a slot machine has $3$ reels with $7$ different symbols on each, jackpot is when all $3$ reels have the same symbol. All three reels are selected independently. What is the probability of getting jackpot on the first try?

My answer $(1/7)^3 = 0.29\%$

2. $X$ represents the number of independent and successive lever pulls to get a jackpot. How many bits of info are conveyed by making a jackpot after $X$ tries?

3. What is the entropy?

I'm pretty clueless on the last two, I'd greatly appreciate any help. Thank you.

• You just need all three to match, not all three to be a specific symbol? If so, the answer to $\#1$ is $\frac 1{7^2}$. – lulu Oct 2 '17 at 16:50
• Please read this tutorial on how to typeset mathematics on this site. – N. F. Taussig Oct 3 '17 at 11:18

for number one, it doesn't matter what the first reel lands on. The other 2 just need to match whatever it is. So its $\left(\frac{1}{7}\right)^2$. If you needed it to land on a specific symbol, then it would be the answer you gave.