Problema Solution
A doctor wished to determine whether a relation exists between the height of
a female and her weight. She obtained the heights and weights of 10 females aged 10 to 24. Let h be the height, measured in inches, and weight w, measured in pounds
h 60 61 62 62 64 65 65 67 68 68
w 100 105 110 112 115 120 124 130 132 137
Find an equation of the regression line for the weight in terms of height (please round all constants to 3 decimal places).
Answer provided by our tutors
we need to find the line of best fit which is the same with equation of the regression line for the weight in terms of height
A line of best fit is a straight line that is the best approximation of the given set of data.
A more accurate way of finding the line of best fit is the least square method.
let
the height value be the x-values
the weight values be the y-values
y = mx + b, where m is slope, b is y-intercept is the line we are looking for
Step 1: Calculate the mean of the x-values and the mean of the y-values: (x0, y0)
x0 = (60+61+62+62+64+65+65+67+68+68)/10 = 64.2
x0 = = 64.2
y0 = (100+105+110+112+115+120+124+130+132+137)/10 = 118.5
y0 = 118.5
Step 2: Compute the sum of the squares of the x-values.
60^2+61^2+62^2+62^2+64^2+65^2+65^2+67^2+68^2+68^2= 41292
Step 3: Compute the sum of each x-value multiplied by its corresponding y-value.
60*100+61*105+62*110+62*112+64*115+65*120+65*124+67*130+68*132+68*137 = 76391
Step 4: Calculate the slope of the line using the formula:
m = (sum (xy) - x0*y0)/(sumx^2 - (sum x^2)/n)
m = (76391 - 64.2*118.5)/(41292 - 41292/10)
m = 1.85086
Step 5: Compute the y-intercept of the line by using the formula:
b = y0 -m*x0
b = 118.5 - 1.85086*64.2
b = -0.325112
Step 6: Use the slope and the y -intercept to form the equation of the line.
y = 1.85086x - 0.325112
y = 1.851x - 0.325
the equation of the regression line for the weight in terms of height is y = 1.851x - 0.325 where x represent the height and y represents the weight.