Studies have shown that people who suffer sudden cardiac arrest have a better chance of survival if a defibrillator shock is administered very soon after cardiac arrest. How is survival rate related to the time between when cardiac arrest occurs and when the defibrillator shock is delivered?The accompanying data givey= survival rate (percent) andx= mean call-to-shock time (minutes) for a cardiac rehabilitation center (in which cardiac arrests occurred while victims were hospitalized and so the call-to-shock time tended to be short) and for four communities of different sizes.

Mean call-to-shock time,x	2	6	7	9	12
Survival rate,y	92	44	31	6	4

(a)Construct a scatterplot for these data.

How would you describe the relationship between mean call-to-shock time and survival rate?

1- There is a strong positive relationship. The relationship is close to being linear, particularly if the point with the lowestxvalueis disregarded. If that point is included then there is the suggestion of a curve.

2- There is a strong positive relationship. The relationship is close to being linear, particularly if the point with the highestxvalueis disregarded. If that point is included then there is the suggestion of a curve.

3- There is a strong negative relationship. The relationship is close to being linear, particularly if the point with the lowestxvalueis disregarded. If that point is included then there is the suggestion of a curve.

4- There is a strong negative relationship. The relationship is close to being linear, particularly if the point with the highestxvalueis disregarded. If that point is included then there is the suggestion of a curve.

(b) Find the equation of the least-squares line. (Round your values to four decimal places.)

= + ( )x

(c) Use the least-squares line to predict survival rate for a community with a mean call-to-shock time of 8 minutes. (Round your answer to three decimal places.)