Question 2 1 pts There are hundreds of street-side ice cream vendors in New York

Question

Question 2 1 pts There are hundreds of street-side ice cream vendors in New York City. A statistician randomly selects ice cream vendors to visit on randomly selected summer days and records two variables: Y total ice cream sales for the day (dollars) and X temperature at noon (degrees Fahrenheit). The statistician builds a linear regression model with the data. Here are some of the numbers the statistician has computed: n-37 sample mean among X observations-75 sample mean among Y observations 382 SSXX 900 SSXY-4320 SSYY-57600 Use this data and story problem to answer the rest of the questions on this quiz. If the association between X and Y is positive, what does this mean? O On average, summer days with a higher noon temperature tend to have higher ice cream sales. On average, summer days with a higher noon temperature tend to have lower ice cream sales Question 3 2 pts What is the slope of the least-squares regression line? Round off to the second decimal place.

Explanation / Answer

2) option A) is correct ,

higher temperu, more the sell

3)

y = a+bx

b = Sxy/Sxx = 4320/900 =4.8

a = ybar - b * xbar = 382 - 4.8 * 75 = 22

y^ = 22 + 4.8 *x

4)

when x = 80

y^ = 22 + 4.8 *80

= 406

5)

r = Sxy/sqrt(Sxx * Syy)

= 4320/ sqrt(900*57600)

= 0.6

r^2 = 0.36

hence 36 % of variation is explained

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