When we conduct a hypothesis test for 1 population proportion, the goal is to determine if the observed sample proportion is "unusual", if we assume
some number for the population proportion. Similar to Joy's ability to smell Parkinson's disease, her success rate was so high that it made it hard to
believe that she was just randomly guessing (p = .5 means she's randomly guessing).
The way we see if a sample proportion is "unusual" is to compute a z-score for the sample proportion: z-scores that are deemed "too far from 0", mean
that the sample proportion is "unexpected" and "too far from the usual number we would expect".
Here's the z-score formula for chapter 10:
$$z = \frac{\hat{p} - p}{\sqrt{\frac{p(1-p)}{n}}}$$
Determine the z-score for Joy's sample proportion. Here are the facts from the experiment: n = 12, x = 11, $\hat{p}$ = 0.9167, p = 0.5
Pro tip for using proportions: use lots of decimal places! If you round your numbers in the middle of your calculations, your final answer will be off. The
answer accepted in this question will be correct if you use either the proportion with all the decimal places, or the proportion with 4 decimal places
and no rounding until the very end.
