Question

The employees of Electronics Inc. would like to have a dental plan as part of their benefits package. The question is: How much does a typical employee and his or her family spend per year on dental expenses? A sample of 56 employees reveals the mean amount spent last year was $1850, with a standard deviation of $700.

a. Construct a 90% confidence interval for the population mean. (Round the final answers to the nearest whole dollar.)

Population mean $  $

b. The information from part (a) was given to the president of Electronics Inc. He indicated he could afford $1730 of dental expenses per employee. Is it possible that the population mean could be $1730?

(Click to select)  Yes.  No.  The population mean  (Click to select)  could be  could not be  $1730 because it is  (Click to select)  in the  not in the  interval constructed above.

Answer 1

a)

sample mean 'x̄=	1850.000
sample size   n=	56.00
sample std deviation s=	700.000
std error 'sx=s/√n=	93.541

for 90 % CI value of z=		1.645
margin of error E=z*std error =		153.86
lower bound=sample mean-E=		1696.14
Upper bound=sample mean+E=		2003.86
from above 90% confidence interval for population mean =(1696 to ,2004)

b)

  Yes The population mean  could be  $1730 because it is in the interval constructed above.