Exam (elaborations)
STAT CHAP 4.2 Questions and and answers (1)
STAT CHAP 4.2 Questions and and answers (1)
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STAT CHAP 4.2Consider the data set given in the accompanying table. Complete parts(a) through
(c).
(b) Find the equation of the line containing the points
(−2,−2) and (2,5).
✅✅
(c) Graph the line found in part(b) on the scatter diagram. Choose the correct graph
below. - -D
The equation of the line is
y= 7/4x+ 3/2.
B
Suppose the line y=2.8333x−22.4967 describes the relation between theclub-head
speed(in miles perhour), x and the distance a golf ball travels(in yards), y.
(a) Predict the distance a golf ball will travel if theclub-head speed is 100 mph.
✅✅
(b) Suppose the observed distance a golf ball traveled when theclub-head speed
was 100 mph was 265 yards. What is theresidual? - -260.8
265-260.8=4.2
✅✅
Which of the following is true of theleast-squares regression line
y=b1x+b0? - -The sign of the linear correlationcoefficient, r, and the sign of the
slope of theleast-squares regressionline, b1, are the same.
Theleast-squares regression line always contains the point x,y.
The predicted value ofy, y, is an estimate of the mean value of the response variable
for that particular value of the explanatory variable.
Theleast-squares regression line minimizes the sum of squared residuals.
A pediatrician wants to determine the relation that exists between achild's height,x,
and headcircumference, y. She randomly selects 11 children from herpractice,
measures their heights and head circumferences and obtains the accompanying
data. Complete parts(a) through(e).
a) Find theleast-squares regression line treating height as the explanatory variable
and head circumference as the response variable.
, (b) Use the regression equation to predict the head circumference of a child who is
25 inches tall.
(c)Compute the residual based on the observed head circumference of the
25-inch-tall
child in the table. Is the head circumference of this child above average or
belowaverage?
d) Draw theleast-squares regression line on the scatter diagram of the data and
label the residual from part(c). Choose the correct graph below.
Is the head circumference of this child above average or belowaverage
-✅✅ -STAT-REGRESSION-LINEAR- COMPUTE FIND WHERE IT SAYS
INTERCEPT AND SLOPE
ENTER 25 FOR PERDICTED X
95% CI MEAN- PRED Y.
B
BELOW AVERAGE
For children who are 26.75 inchestall, head circumference varies.
A student at a junior college conducted a survey of 20 randomly selectedfull-time
students to determine the relation between the number of hours of video game
playing eachweek, x, andgrade-point average, y. She found that a linear relation
exists between the two variables. Theleast-squares regression line that describes
this relation is
y=−0.0578x+2.9274.
(a) Predict thegrade-point average of a student who plays video games 8 hours per
week.
b) Interpret the slope.
(c) Ifappropriate, interpret they-intercept.
(d) A student who plays video games 7 hours per week has agrade-point average of
2.63.
✅✅
Is thestudent's grade-point average above or below average among all students
who play video games 7 hours perweek? - -The predictedgrade-point average
is 2.47
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