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.

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

  • $\begingroup$ While I agree with this, it doesn't answer the whole question. $\endgroup$ – Matti P. Oct 3 '17 at 11:24

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