Practice!

Sample Problem

Year

The number of jalapenos on Mars (in thousands)

1970

40

1971

40

1972

42

1973

47

1974

54

1975

57

1976

63

1977

65

1978

68

1979

77

1980

81

1981

82

1982

88

1983

92

1984

95

1985

99

1986

100

1987

110

1988

114

1989

121

1990

130

 

Why is it so hot on Mars? Since they discovered the fourth planet from the Sun, scientists have been in the midst of heated debates and deep speculation. Last year, a scientist named John Kosher Shaw from Dirty Potato Chipville, Louisiana noticed an uncanny growth of jalapeno pepper populations on the planet. Could this be the reason why Mars is so hot? Above is a table of the number of jalapeno peppers on Mars (in the thousands) over a 20 year period (1970-1990).

Let t=0 represent the year 1970 and let y represent the number of jalapeno peppers (in thousands) on Mars.

Your task is, using the linear regression feature on your graphing calculator, find a least squares regression line to predict, based on this trend, what the jalapeno pepper populations were after 1990.

 

y=x+ (round your answers to the nearest tenth)

Solution

 

After plugging in all the values into the graphing calculator (remember to replace the actual years with the year numbers, starting with 1970= Year 0, 1971=Year 1…etc.), your graph should look something like this. Using the linear regression function on the graphing calculator, you should be able to get the slope and y-intercept value of the “best-fit” line, or least squares regression line.

LinReg

y=ax+b

a=4.397402597

b=35.31168831

y=4.4x+35.3