With $N=40$ (even), the median needs the 20th and 21st observations, located via a cumulative frequency column, before deviations from it can be measured.

Step 1 — Build the cumulative frequency table.

Check: $\sum f=4+9+14+8+5=40$, matching the stated 40 days.

Step 2 — Locate the median. $N=40$ is even, so the median is the average of the 20th and 21st observations. The c.f. after $x=1$ is 13 (observations 1–13), and the c.f. after $x=2$ is 27 (observations 14–27). Both the 20th and the 21st observation fall in this second group, so both equal 2. Median $M = (2+2)/2 = 2$.

Step 3 — Find $|x-M|$ and $f|x-M|$ for each row.

| $x$ | $f$ | $|x-2|$ | $f|x-2|$ |

|---|---|---|---|

| 0 | 4 | 2 | 8 |

| 1 | 9 | 1 | 9 |

| 2 | 14 | 0 | 0 | …

Assuming the median must be a single clean value read straight off the c.f. column, without checking whether the 20th and 21st observations fall in the SAME class (as they do here) or in different classes, is the standing slip …