Question

With 90% confidence, for sample mean 400.50, sample standard deviation 11.50, and sample size 35, what is the upper confidence limit with 2 decimal places

Answer 1

b )Given that,

= 400.50

s =11.50

n = 35

Degrees of freedom = df = n - 1 = 35 - 1 = 34

At 90% confidence level the t is ,

= 1 - 90% = 1 - 0.90 = 0.1

t /2,df = t0.1,34 = 1.307 ( using student t table)

Margin of error = E = t,df * (s /n)

= 1.307* ( 11.50/ 35) = 2.54

The 90%upper confidence interval estimate of the population mean is,

< + E

< 400.50+ 2.54

< 403.04