Sales of a product on any given day are normally distributed with a mean of $100 and a standard deviation of $8.
Out of 200 days, on how many days would the sales be expected to be between $84 and $108?
- 82
- 95
- 163
- 190
Show Worked Solution
\(z\text{-score \$84} = \dfrac{84-100}{8}=-2\)
\(z\text{-score \$108} = \dfrac{108-100}{8}=1\)
\(\text{\% days between \(z\)-score 1 and}\ -2 = 68+13.5=81.5% \)
\(\text{Number of days} = 0.815 \times 200 = 163\)
\(\Rightarrow C\)