Question

With 90% confidence, for sample mean 334.00, sample standard deviation 10.40, and sample size 35, what is the upper confidence limit with 2 decimal places?

Answer 1

Solution :

Given that,

Point estimate = sample mean = = 334.00

Population standard deviation =    = 10.40
Sample size = n =35

At 90% confidence level the z is

= 1 - 90% = 1 - 0.90 = 0.1

= 0.1

Z = Z0.1 = 1.28 ( Using z table )

Margin of error = E = Z * ( /n)

=1.28 * (10.40 /  35 )

=2.2501
At 90% confidence interval estimate of the population mean
is,

+ E

334.00 +2.2501

336.2501

upper limit=336.2501