4. In the U.S., from 2004 – 2015, the correlation coefficient for the relationship
between the size of a cell phone data plan, x, and the number of text
messages sent, y, is r = +0.97. Describe the relationship between the data
plan size and the number of text messages sent in the U.S. Use complete
sentence(s).

In statistics, the correlation coefficient is attributed to a symbol R. Correlation Coefficient value spread over a range from -1 to +1. It shows the depth of relationship between the movement which is relative of two existing variables

From the given question;

We have the study of the relationship between the data plan size and the number of text messages sent in the U.S.

When R value is at 0 ; it illustrates and pinpoint the fact that there is no relationship between these two variables under study.

However; the R value near to +1 and -1 definitely shows the strength of the positive and negative correlation of the two variables under study.

Given that :

R = +0.97 ; we can see from above explanation that this is showing and telling us that there is a strong positive correlation coefficient for the relationship between data plan size 'x' and number of text messages sent 'y'.

Conclusion: we conclude that the large data size corresponds to the large number of text messages and the small data size corresponds to the small number of text messages.