```
I have few clarification on this calculation.
1. If we need 90% confidence, then alpha = 0.1. But, alpha is shown as 0.9. Is it correct ?
2. If alpha = 0.1 => 1-alpha = 0.9 => z=1.282 => mu < bar(X) + 1.282 * 1/Sqrt(25) => bar(X) + 0.2564, But in session its shown as 0.33. Is it correct ?
3. similarly please confirm on interval estimate too. I'm getting bar(x) - 0.329 < mu < bar(x) + 0.329.
```

- I think (1 - alpha) is mentioned as 0.05 by mistake on right hand side of the equation instead of 0.95
- When I calculate, I get Z(0.95) as 1.645 and mu < 32.35. Can you please confirm, if the calculation showed in the video is correct

Hi @venkatachalamramalin,

Yes you’re right…

- Alpha is indeed the critical point, but it’s mentioned as 0.9 here, which is incorrect. It should have been 0.1 instead.

- Yes, i think the z score reading from the table was taken incorrectly here. You’re right, it should have been 0.2564 instead of 0.33

- Yes, the same applies to this as well, it might be an error in reading the z-score. It should be 0.329.

- Yes, It should have been 0.95

- Yes you’re right, i think the z-score is the cause for this miscalculation here as well.

Thanks for pointing all these errors, have noted them down.

Can you please also mark Week and Video name in the header, so that it becomes convenient for someone else searching for the same doubt.