Lab 1280 - Slot Machine


In this lab, you will model a slot machine. The machine accepts a dollar from you. Then you spin the reels. When the reels stop spinning, if the symbols line up in a winning combination, you win money from the machine.

Our slot machine has three reels with symbols on some of the 32 possible stop positions for each reel. Many stop positions are blank. Table 1 shows the frequency of each symbol on each reel. Each stop is equally likely.

Table 1: Reel Strips

Stop Reel 1 Reel 2 Reel 3
1 Blank Seven Bars
2 Bars Cherries Blank
3 Blank Bars Blank
4 Blank Bars Blank
5 Bars Blank Cherries
6 Blank Bars Blank
7 Cherries Blank Seven
8 Seven Blank Bars
9 Bars Seven Blank
10 Blank Blank Bars
11 Blank Blank Blank
12 Bars Cherries Blank
13 Seven Blank Bars
14 Cherries Blank Blank
15 Seven Blank Cherries
16 Blank Bars Seven
17 Seven Blank Blank
18 Bars Blank Seven
19 Seven Blank Blank
20 Blank Cherries Bars
21-32 Blank Blank Blank

As a practical note, these are actually virtual reels. A physical reel does not have 32 stop positions. These 32 virtual positions map to one of twenty actual positions. This makes the physical reel small enough to fit in the machine and also makes it appear to have more symbols and a higher chance of payoff.

After our hypothetical dollar is put in the machine, the customer spins the reels. Each reel spins independently and stops on one of the thirty-two equally-likely positions. Once the machine has stopped, some combinations of symbols reward the player with a payout. Here is the pay table for this hypothetical machine:

Table 2: Pay Table
Symbols on Pay Line Payout
three sevens $250
three bars $75
three cherries $12
exactly two cherries $8
only one cherry $2

Create a class to model the slot machine described in the tables above. For this machine, the bet is always one dollar. Calculate the expected return on this slot machine by playing many games and then dividing coins won by coins in. For example, if in 100 plays of one dollar each you win a total of $98, we say the return on the machine is 98%. You should write a file to track coins in and coins won and report the return on the machine.

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