The correlation coefficient is measured in the same units as the variables.

Consider the following card game with a well-shuffled deck of 52 cards. You win 3 € if you draw a black king or a spade and 7 € if you draw a heart or a red queen. If you draw any other card you win nothing.

What is the maximum amount you would be willing to pay to play this game?

Covariance is affected by the scale of the variables.

A telephone number is selected at random from a directory. Suppose that  denote the last digit of selected telephone number. The average and the variance of are, respectively,

The cumulative probability function of the daily number of customers visiting a retail store during a specific time slot () is given in the table below.

The expected value and variance of the daily number of costumers visiting the store are, respectively,

Let be a random variable that represents the number of brand B products that are purchased per day in a small market. The average and the standard deviation of the number of brand B products that are purchased per day are 2 and 0.5, respectively

It is known that the relationship between the number of brand C products that are purchased in this market per day, , and the variable is given by . The mean and variance of are, respectively,

Which correlation coefficient best matches the scatterplot shown below?