Question

A city manager made a scatter plot of the number or retail store in a certain city over the years. the scatter plot had a trend line with an equation of y=11x + 12, where y is the total number of retail stores and x is the number of years since 1990. Tracy and her family moved to the city in 2003. Use the equation to predict how many retail stores there were in 2003?

Answer 1

155

Explanation:

The problem sounds complicated, but it's not. Let's analyse.

The city manager have come up with an equartion y=11x +12, with Y is the total number of the stores and X stands for how long it has been since 2003.

We can't explain how the manager came up with this equation, so iwe don't need to think of if the equation is real or not. Let's just base on what we have.

Because the equation aboce is a trendy line, it means that it would likely to be true with any X ( number of years since 1990).

In Tracy's case, the year is 2003, so it has been 2003 - 1990 = 13 years since 1990. This is the X in the equation. Now we only need to find Y in the equation, which is the number of retail stores there were in 2003, exactly what the problem asks.

y= 11x + 12

=> In Tracy's case: y= 11*13 + 12= 155

So the number of retail stores there were in 2003 was 155