A bakery kept a record of the number of loaves of bread a tuck-shop ordered daily over the last 18 days - NSC Mathematics - Question 1 - 2021 - Paper 2

The standard deviation ($\sigma$) is calculated as follows:

1. Calculate the variance by finding the squared differences from the mean and averaging them:

$\sigma \approx 10.1707 \\ ext{then, } \sigma \approx 10.17$

Thus, the standard deviation of the data is 10.17.

The mean is 22 and one standard deviation above the mean is:

$\bar{x} + \sigma = 22 + 10.17 = 32.17$

Next, we check how many days ordered more than 32.17 loaves:

• Days with orders: 35, 37, 40, 41

This gives us 4 days.

The total ordered is 396 loaves and the total sold over 18 days is:

$20 \times 18 = 360$

Thus, the number of loaves not sold is:

$396 - 360 = 36$

So, the number of loaves of bread which were NOT sold is 36.

Graph B is correct.

Reason: The median (18.5), first quartile (Q1 = 14), and third quartile (Q3 = 21) align with the values derived from the data.

The data is positively skewed.

This indicates that the mean is greater than the median, as outliers on the right pull the tail longer.