STA1013 section 07 Sampler Test 3 Chapter 14_ 15_ 17 1 The .rtf

							STA1013 section 07 Sampler Test 3
Chapter 14, 15, 17


   1.   The correlation between two variables is of –0.8. We can conclude
   A)   one causes the other
   B)   there is a strong positive association between the two variables
   C)   there is a strong negative association between the two variables
   D)   all of the relationship between the two variables can be explained by a straight line
   E)   there are no outliers


   2. The correlation between two variables x and y is 0.5. If we used a regression line to
      predict y using x, what percent of the variation in y would be explained?
   A) 50%
   B) 25%
   C) 2.23%
   D) 75%
   E) 0%


   3. If the least squares regression line for predicting y from x is y = 500 – 20x, what is the
      predicted value of y when x = 10 ?
   A) 300
   B) 500
   C) 200
   D) 700
   E) 20


   4.   Which correlation indicates a strong positive straight line relationship?
   A)   0.4
   B)   –0.75
   C)   1.5
   D)   0.0
   E)   0.99


   5.   In a scatterplot we can see
   A)   a display of the five-number summary
   B)   whether or not we have a simple random sample
   C)   the shape, center, and spread of the distribution of a quantitative variable
   D)   the form, direction, and strength of a relationship between two quantitative variables
   E)   Kansas




                                               Page 1
The stock market did well during the 1990s. Here are the percent total returns (change in price
plus dividends paid) for the Standard & Poor's 500 stock index:

Year      1989    1990    1991    1992    1993     1994    1995    1996    1997    1998
Retur      31.7    –3.1    30.5     7.6    10.1      1.3    37.6    23.0    33.4    28.6
n



    6. The correlation of U.S. stock returns with overseas stock returns during these years was r
       = 0.44. This tells you that
    A) when U.S. stocks rose, overseas stocks also tended to rise, but the connection was not
       very strong
    B) when U.S. stocks rose, overseas stocks rose by almost exactly the same amount
    C) when U.S. stocks rose, overseas stocks tended to fall, but the connection was not very
       strong
    D) there is almost no relationship between changes in U.S. stocks and changes in overseas
       stocks
    E) nothing, because this is not a possible value of r


    7. If x is the return on U.S. stocks and y is the return on overseas stocks in the same year, the
       least-squares regression line for predicting y from x is y = –2.7 + 0.47x . You think U.S.
       stocks will have a return of 10% in 1999. Using this regression line, you predict that the
       return on overseas stocks will be
    A) 7.4%
    B) –2.23%
    C) 2%
    D) 3.17%



The correlation between the heights of fathers and the heights of their (grownup) sons is r = 0.52 .


    8.   This tells us that
    A)   taller than average fathers tend to have taller than average sons.
    B)   taller than average fathers tend to have shorter than average sons.
    C)   sons are, on the average, taller than their fathers.
    D)   52% of all sons are taller than their fathers.
    E)   there is almost no connection between heights of fathers and sons.




                                                  Page 2
9.   Perfect correlation means all of the following except
A)   r = –1 or r = +1.
B)   all points on the scatterplot lie on a straight line.
C)   all variation in one variable is explained by variation in the other variable.
D)   there is a causal relationship between the variables.
E)   each variable is a perfect predictor of the other.


10. A study of the effects of television measured how many hours of television each of 125
    grade school children watched per week during a school year and their reading scores.
    The study found that children who watch more television tend to have lower reading
    scores than children who watch fewer hours of television. The study report says that
    "Hours of television watched explained 9% of the observed variation in the reading scores
    of the 125 subjects." The correlation between hours of TV and reading score must be
A) r = 0.09
 B) r = –0.09
 C) r = 0.3
D) r = –0.3
 E) Can't tell from the information given.


11. Consider the following data:

     x         3         6         –7         1         –5
     y        –3        –6          7        –1          5

     The correlation coefficient r is
A)   7.6
B)   0.0
C)   1.0
D)   –0.6
E)   –1.0




                                             Page 3
Answer Key

   1.   C
   2.   B
   3.   A
   4.   E
   5.   D
   6.   A
   7.   C
   8.   A
   9.   D
  10.   D
  11.   E




             Page 4