Posted by D on .
In a survey of 400 college students, 40 were left-handed. Treating the sample as if it were random and using 0.015 as the standard deviation of the sampling distribution of the sample proportion, what is the lower bound of a 95% confidence interval for the population proportion?
Use a proportional confidence interval formula:
CI95 = p + or - (1.96)(0.015)
...where p = x/n
Note: + or - 1.96 represents 95% confidence interval.
For p in your problem: 40/400 = .1
I let you take it from here to calculate the interval.