{(1,0.5)(2,0.25)(3,0.125)(4,0.0625) } which kind of model best describes the data set?

  exponential: y = 2^(-x)

Step-by-step explanation:

The y-differences are not constant, and the x-y products are not constant. For each increase in x, y is divided by 2, so this is a geometric sequence that can be described by an exponential model. The common factor is 1/2.

A simple way to write the model for this is ...

  y = 2^(-x)

175

step-by-step explanation:

2 inches x 10 miles = 200 miles - 3 inches = 175

4 and 5)16.97 or 12√2

6)15.59 or 9√3

7)y = 15.59 or 9√3     x =27

8)17.80