Based on this scatter plot, whatcan you say about the relationship between study time and test scores?

Based on this scatter plot, I can say that in general, test scores vary directly with study time.  In other words, in a population large enough to reveal the direct relationship, the more time a student spends studying, the higher that student's test scores will be.

I didn't need a scatter plot to reveal that to me.  That's practically in the category of Law given to Moses at Sinai.

it is a negative acceleration