Question

College Graduation Rates. Data from the College Results Online website compared the 2011 graduation rate and median SAT score for 92 similar-sized public universities and colleges in the United States. The scatterplot below shows the relationship between these two variables along with the least squares fit. Round all calculated results to 4 decimal places.

1. The relationship between median SAT score and graduation rate is  ? positive negative ,  ? weak strong , and  ? linear non-linear .

2. The explanatory variable is  ? graduation rate median SAT college year  and the response variable is  ? graduation rate median SAT college year .

The summary statistics for graduation rate and median SAT score are listed below. The correlation between graduation rate and median SAT score is 0.649.

Median SAT score: mean = 1033.3, standard deviation = 80.1
Graduation rate: mean = 51.8, standard deviation = 13.7

3. The equation of the regression line is y =  +  x

4. Complete the following sentence to interpret the slope of the regression line:

An increase of  in Median SAT score corresponds to a/an  ? decrease increase  of  in Graduation Rate.

5. The recorded median SAT score for Northern Michigan University is 1028. Use the regression equation to estimate the graduation rate for Northern Michigan University.  

6. The recorded graduation rate for Northern Michigan University is 47.6. Complete the following sentence.

The residual for Northern Michigan University is  . This means the graduation rate at Northern Michigan University is
A. higher than
B. lower than
C. the same as
the rate predicted by the regression model.

7. Stanford University (an elite private university in California not included in this data set) has a median SAT score of 1455. Would it be appropriate to use this linear model to predict the graduation rate for Stanford?

A. No, because 1455 is beyond the range of the data used to build the regression model.
B. No, because 98.610% is too large to be a reasonable graduation rate, even for an elite university.
C. Yes, because 1455 is a reasonable median SAT score for an elite university.

Answer 1

The relationship between median SAT score and graduation rate is  positive weak and  linear

2_)

The explanatory variable is   median SAT   and the response variable is Graduation rate

3)

	x̅ =		1033.3
	y̅ =		51.8
	sx=		80.1
	sy =		13.7
	r=		0.649
slope b1=r*sy/sx=			0.1110
intercept bo=y̅ +r(sy/sx)*(x̅)=			-62.8989

y^ =-62.8989+0.1110*x

4_)

An increase of 1 in Median SAT score corresponds to a increase  of 0.1110  in Graduation Rate.

5)

predicted value =0.111002496878901*1028+-62.8988800249688=

51.2117

6)

residual =47.6-51.2117 =-3.6117

B. lower than

A. No, because 1455 is beyond the range of the data used to build the regression model.