In: Statistics and Probability
Given: Assume you have collected data from 150 subjects, and that the distribution of the data is a "normal" distribution. The mean of the scores is 37, with a standard deviation of 4.5. Using the given information, calculate the 68% confidence interval. A confidence interval represents a range of values, the lowest value is references as the "lower bound", the highest value is referenced as the "upper bound". Determine the lower and upper bounds for the 68% confidence interval. Round your answer for each value to a single decimal place (e.g. 36.63 rounds to 36.6).
Lower Bound =
Upper Bound =
Solution :
Given that,
= 37
= 4.5
n = 150
At 68% confidence level the z is ,
= 1 - 68% = 1 - 0.68 = 0.32
/ 2 = 0.32 / 2 = 0.16
Z/2 = Z0.16 = 0.995
Margin of error = E = Z/2* ( /n)
= 0.995 * (4.5 / 150)
= 0.37
At 68% confidence interval estimate of the population mean is,
- E < < + E
37 - 0.37< < 37 + 0.37
36.63< < 37.37
(36.63 , 37.37 )
lower bound =36.63
upper bound = 37.37