# Thread: Probability question

1. ## Probability question

When you give the Venetian casino in Las Vegas $5 for a bet on the number 7 in roulette, you have a 37/38 probability of losing$5 and you have a 1/38 probability of making a net gain of $175. I did$-5 x 37/38(.974) = -4.87
I did $5 x 1/38(.026) = + 0.13 = -4.74. The answer is -. 26 cents. What did I do wrong? 2. Hello, rowdy3! When you give the Venetian casino in Las Vegas$5 for a bet on the number 7 in roulette,
you have a $\displaystyle \tfrac{37}{38}$ probability of losing $5 and you have a$\displaystyle \tfrac{1}{38}$probability of making a net gain of$175.

I did: .$\displaystyle (-5)\times \frac{37}{38} \:\approx\: -4,87$

I did: .$\displaystyle 5 \times \frac{1}{38} \:\approx\:+0.13$
. - . . .$\displaystyle {\color{red}\uparrow}$

The answer is $\displaystyle -\$0.26$What did I do wrong?$\displaystyle \begin{array}{cccc}\text{We lose \$5 with probability }\tfrac{37}{38} & (-5)\left(\tfrac{37}{38}\right) &\approx& -\$4.87 \\ \\[-3mm]

\text{We win {\color{red}\$175} with probability }\tfrac{1}{38} & (+175)\left(\tfrac{1}{38}\right) &\approx& +\$4.61 \end{array}\$

Got it?

3. thank you very much.