You are interested in purchasing a new car. one of the many points you wish to consider is the resale value of the car after 5 years. since you are particularly interested in a certain foreign sedan, you decide to estimate the resale value of this car with a 90% confidence interval. you manage to obtain data on 17 recently resold 5-year-old foreign sedans of the same model. these 17 cars were resold at an average price of $12,630 with a standard deviation of $800. suppose that the interval is calculated to be ($12,291.23, $12,968.77). how could we alter the sample size and the confidence coefficient in order to guarantee a decrease in the width of the interval?

There are 3 ways to decrease the width of the interval

Step-by-step explanation:

First way:  Reduce the level of confidence.  This drops the error value, since we are saying we are less confidence in the interval, we can have a smaller interval.  Say we drop it to 80%, that means that we are only 80% confident that we are correct, so we're admitting to being wrong 20% of the time.  

Second way:  Increasing the sample size will reduce the error value, which will decrease the interval.  

Third way:  Reduce the level of confidence and increase the sample size.  This is a combination of both previous methods.

the required function is .

step-by-step explanation:

from the given table it is noticed that the graph passing through (-3,7), (0,4), (3,1) and (8,-4).

it is a linear function because the value of y is decrease by one as the value of x increase by 1.

the slope of the function is

the slope of the function is -1 and the y-intercept is 4.

the slope intercept form is

where, m is slope and b is y-intercept.

therefore the required function is . the graph of this function is shown below.

c

step-by-step explanation: