Ok listen,
For 20< x < 22 it says that the height is 11.5 which can be done by dividing 115 by 2, and then by 5
Cuz for these type of questions u need to divide the frequency by the range and then divide or multiply or add or subtract to get a similar answer to the given one...
This questions is quite easy however I still have a doubt in finding the possible values of the median but the rest is fine...