A company made some tests for a material humidity with these results:
HUMIDITY ............... FREQUENCY
- 18.75 - 19.75 % ... 3
- 19.75 - 20.75 % ... 22
- 20.75 - 21.75 % ... 123
- 21.75 - 22.75 % ... 300
- 22.75 - 23.75 % ... 201
- 23.75 - 24.75 % ... 61
- 24.75 - 25.75 % ... 6
- 25.75 - 26.75 % ... 1
Using point estimation calculate the expected value and the standard deviation... I have no idea how to calculate it since I don't have values but intervals in percentage...
[RESULT: expect.value: 22.486, stand.dev. : 0.998%]