Question

The linearized regression equation for an exponential data set is log ŷ = 0.14x + 0.4, where x is the number of years and y is the population. What is the predicted population when x = 15? Round your answer to the nearest whole number.
A.3
B.126
C.316
D.9537

Answer 1

Option C: $316$ is the predicted population when $x=15$

Explanation:

The regression equation for an exponential data is $\log y=0.14x+0.4$

Where x is the number of years and

y is the population

We need to determine the predicted population when $x=15$

The population x can be determined by substituting $x=15$ in the equation $\log y=0.14x+0.4$

Thus, we have,

$\log y=0.14(15)+0.4$

$\log y=2.1+0.4$

$\log y=2.5$

Using the logarithmic definition $\log _{a}(b)=c$ then $b=a^{c}$

$\log _{10}(y)=2.5 \Rightarrow y=10^{2.5}$

$y=316.22776 \ldots$

Rounding off to the nearest whole number, we get,

$y=316$

Thus, the predicted population when $x=15$ is 316

Hence, Option C is the correct answer.