# Math Help - Estimation

1. ## Estimation

In a normal population with standard deviation = 5, withdraw a sample of 50 elements and we obtain mean = 42.

a) Determine a confidence interval for the mean level of 5%.
b) What is the estimation error at 5%?
c) To the error is <= 1, with probability of success of 95%, which should be the sample size?

2. $42\pm (1.96)5/\sqrt{50}$

$(1.96)5/\sqrt{50}$

Set $(1.96)5/\sqrt{n}\le 1$ and solve for n

3. Originally Posted by matheagle
$42\pm (1.96)5/\sqrt{50}$

$(1.96)5/\sqrt{50}$

Set $(1.96)5/\sqrt{n}<1$ and solve for n
Thanks