An analyst would like to predict water consumption in a city based on daily temperature. She has gathered the following data for a random sample of n=7 days.
Temperature Water Consumption
(x) (million gallons) (y)
40 225
5 25
25 150
15 100
10 75
30 125
35 175
Ex=160, Ey=875, SSxx=1042.857, SSyy=26250, SSxy=5000
a) Describe the type of relationship that would be expected between temperature and water consumption.
b) Test at the 2.5% level of significance whether B is positive. Use the critical value approach. Assume sb=0.6609
c) Construct a 90% prediction interval for the water consumption on a particular day when the temperature is 28 degrees Celsius. Assume Se= 21.34