Sushri Sandhya has already written the sizes in ascending order:
| Shoe size | Tally marks | Number of students |
|---|---|---|
| 3 | ||| | 3 |
| 4 | 9 | |
| 5 | 10 | |
| 6 | |||| | 4 |
| 7 | | | 1 |
| Total | — | 27 |
a. 7 — the last number in the ordered list.
b. 3 — the first number in the ordered list.
c. 10 students wear size 5.
d. 15 students wear a size larger than 4.
= 10 + 4 + 1 = 15