Bivariate and Univariate Data Revision

The value of r-correlation coefficient is always:

• 0 $-1\le r\le1$

• $r>1\ or\ r<-1$

• $0<r<1$

• $-1<r<-1$

Pearson's correlation coefficient is used to

• find the standard deviation of the response variable

• find how strongly two variables are associated

• how good looking the scatterplot is

• the gradient of the regression line

The correlation coefficient of -0.95 implies

• strong positive association

• weak negative association

• weak non-linear association

• strong negative association

Estimate the correlation coefficient of

the scatter plot shown above

• 0.75

• -0.99

• 0.13

• -0.88

Which of the following statements is correct?

• x axis stands for independent variable and y axis stands for dependent variable.

• Scatter plots can be used to describe relationships between categorical data.

• Explanatory variable should be on the y axis

• Response variable should be on the x axis

A pie seller at a football match finds that the number of pies (N) he sells is related to the temperature (t) in degrees Celsius of the day. The situation could be modelled by the equation

N = -25t + 775.

The predicted temperature during the day on which 475 pies are sold is:

• 8 degrees

• 9 degrees

• -10 degrees

• 12 degrees

From a box plot, you cannot find

• the median

• the mean

• the range

• the third quartile

The median age of males in a town getting married is 32 years old. Which of the following is correct?

• All males get married after 32 years old.

• The average marriage age is 32 years old.

• Less than 50% of males do not get marriage before 32.

• 32% of males are married in this town.

The shape of the box plot is

• symmetrical

• spread out

• negatively skewed

• positively skewed

The following equation can be used to predict the relative humidity (%) on any given day from its temperature (in °C).

humidity=95−2.05×temperature

The intercept for this regression equation predicts that

• When the humidity is 0%, the temperature is 0° C

• When the humidity is 95%, the temperature is 2.05° C

• When the temperature is 0° C, the humidity is 95%

• When the temperature is −2.05° C, the humidity is 95%

• When the temperature is 95° C, the humidity is −2.05%