Question

7. Based on an exponential model of the data, what is the predicted value of Variable 2 when

Variable 1 = 2?
Round your answer to the nearest whole number.
Variable 1:
10
20
30
40
50
60
70
80
90
100
variable 2:
100
80
52
40
35
25
17
11
10
7

Answer 1

128

Explanation:

You want a prediction for x=2 when the given data is modeled by an exponential model.

• x = 10, 20, 30, 40, 50, 60, 70, 80, 90, 100
• y = 100, 80, 52, 40, 35, 25, 17, 11, 10, 7

Model

A graphing calculator's exponential regression function models this data with the formula ...

y = 135.7 · 0.9711^x

y = 137.7 · 0.9711^2 ≈ 127.94 . . . . when x=2

This model gives a value for variable 2 of approximately 128 when variable 1 = 2.

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