SAT Two-Variable Data study notes

SAT scatterplots ask you to read a model, not just a dot. Check whether the pattern is roughly linear or curves, then use the values and units on the axes. In an exponential model y = a(b^x), a is the value at x = 0 and b is the multiplier for each increase of 1 in x.

Worked example

The labeled points on the model are (0, 80) and (1, 64). If y = a(b^x), what is b?

At x = 0, a = 80. One x-step later, the output is 64, so b = 64/80 = 0.8. The curve goes down because a multiplier between 0 and 1 makes each new output smaller.

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