#### StatsSeeker

##### New member

- Joined
- Jan 8, 2019

- Messages
- 1

I wanted to check I haven’t made a mistake with something:

I have a range of percentage errors and i need to test that the percentage error rate is >20%, Then I need to find the confidence error level (95%) for the population mean.

I basically took the mean of the figures below and it = 26 and then used this mean to calculate the confidence internal (using the standard deviation, which was 3.31)

I got 24.9-27.2

Can some please advise if I have done something wrong.

Thank you and much appreciated.

Here are the numbers

31.7 | 21.7 | 20.7 | 21.7 | 29.7 | 25.7 | 24.7 | 27.7 | 28.7 |

25.7 | 28.7 | 27.7 | 23.7 | 21.7 | 31.7 | 27.7 | 27.7 | 25.7 |

19.7 | 25.7 | 27.7 | 23.7 | 24.7 | 30.7 | 26.7 | 22.7 | 28.7 |