A group of learners wrote a standardised English test that was scored out of 60. The results were represented in a cumulative frequency graph below. How many learners wrote the test?

The graph shows that the cumulative frequency reaches its maximum value and flattens out at 80. This represents the total number of learners who wrote the test.
The number of learners who wrote the test is $\boxed{\text{80}}$.

Locate 20 on the "Marks obtained" (x-axis). Move vertically up to the curve, then horizontally to the "Cumulative Frequency" (y-axis).
At 20 marks, the cumulative frequency is 20. This means 20 learners scored less than 20 marks.

Subtract the number of learners who scored less than 20 from the total number of learners.

The number of learners who scored at least 20 out of 60 is $\boxed{\text{60}}$.

The median is the middle value. For 80 learners, the median position is at $\frac{80}{2} = 40$.

Find 40 on the "Cumulative Frequency" (y-axis). Move horizontally across to the curve, then vertically down to the "Marks obtained" (x-axis).
The corresponding mark is approximately 30.
The estimated median test score is $\boxed{\text{30}}$.