Probability of Combined Events: GCSE Maths Question of the Week

[bananajuice]

I’m doing GCSEs this is a very good and funny video

[ratma]

The 2/20 wrong answer is probably from the question asking to spin "twice". A student may be finally tricked into saying 2/20 because you have to spin them twice instead of 2/40 which simplifies down to 1/20. I have had some student feedback which confirms this. It is hard to explain that the second spin doesn't increase the chances, but it was fun.