We wish to give a 90% confidence interval for the mean value of a normally distributed random variable. we obtain a simple random sample of 9 elements from the population on which the variable is defined. the sample has a mean value of 10.2 and a sample standard deviation 1.5. find the 90% confidence interval for the mean value.

Step-by-step explanation:

Given : Sample size : n= 9

Degree of freedom = df =n-1 =8

Sample mean :

sample standard deviation :

Significance level ;

Since population standard deviation is not given , so we use t- test.

Using t-distribution table , we have

Critical value =

Confidence interval for the population mean :

90% confidence interval for the mean value will be :

Hence, the 90% confidence interval for the mean value=

answer: since the question is talking about growth you have to use the growth formula which is inital amount (1 + growth)^time

step-by-step explanation:

the intial amount is 1200, the growth is 4.8, and the time is 7. plug those numbers into the equation, also i think you have to change 4.8 into a percent. but, i have forgotton how to do that. if this is a online class go on to the lesson.

the answer is 31.27mph