Question

A coastal geologist estimates that a certain country's beaches are eroding at a rate of 1.51, point, 5 feet per year. According to the geologist's estimate, how long will it take, in years, for the country's beaches to erode by 21 feet?

Answer 1

14 years.

Explanation:

Let x represent number of years.

We have been given that a coastal geologist estimates that a certain country's beaches are eroding at a rate of 1.5 feet per year. We are asked to find the number of years, it will take for the country's beaches to erode by 21 feet.

We will use proportions to solve our given problem as proportion states that two quantities are equal:

`\frac{\text{Erosion in feet}}{\text{Number of years}}=(1.5)/(1)`

Upon substituting our given values in above equation, we will get:

`(21)/(x)=(1.5)/(1)`

Let us cross multiply our equation as:

`1.5x=21*1`

`1.5x=21`

Divide both sides by 1.5:

`(1.5x)/(1.5)=(21)/(1.5)`

`x=14`

Therefore, it will take 14 years for the country's beaches to erode by 21 feet.