I'm not 100% sure, because i don't have graphing calculator on me, but the correlation coefficient is how well the line of best fit goes with the data, and the data points on the graph look like they match the line. The closer the correlation coefficient is to 1 or -1, means that it has a strong correlation coefficient. It's negative because the slope of the line is negative. If you really want to make sure, you can plug it into a graphing calculator in STAT.
A linear relationship is said to be strong if the points on graph are close to a straight line ( correlation coefficient is nearest to 1) and weak if they widely scattered about the line ( correlation coefficient is nearest to -1) .
From the given graph it appeaser to be a strong negative correlation as the points are moving downwards diagonally close to a line which shows if one variable increases , the other decreases.
It means the correlation coefficient must be the nearest value to -1, i.e. -0.91.
Thus, the correlation coefficient most likely for the set of data shown =-0.91
