The table shows the lengths of 50 leaves collected on a nature walk, with two frequencies x and y missing.

Explanation

1. 01

   Total: $6 + x + 18 + 12 + y = 50$, so $x + y = 14$.

2. 02

   $n \div 2 = 25$ falls in 20–30, with cf before it $= 6 + x$, $f = 18$, $h = 10$.

3. 03

   $25 = 20 + \frac{25 - (6 + x)}{18} \times 10$, so $\frac{19 - x}{18} \times 10 = 5$.

4. 04

   $19 - x = 9$, giving $x = 10$ (and $y = 4$).