5. A hamburger restaurant knows that its average daily sales has mean of $2800 with standard deviation of $200. What does it mean that "yesterday's average sale had a z-score of -3"? (a) yesterday they had a loss (b) yesterday's sales was 3 standard deviations below the mean (i.e. $2200) (c) yesterday's sales was 3 standard deviations above the mean (i.e. $3400) (d) yesterday's sale was $3 below the mean (i.e. $2795)