Question

A sand dune stands 5 feet above sea level. The hill is eroding at a rate of 1 foot per 20 years. Let y represent the height of the sand dune after x years. Which equation represents the situation?

y = negative StartFraction 1 Over 20 EndFraction x minus 5

y = negative StartFraction 1 Over 20 EndFraction x + 5

y = negative 20 x minus 5

y = negative 20 x + 5

Answer 1

The sand dune is eroding at a rate of 1 foot per 20 years. This means that for every 20 years that pass, the height of the sand dune decreases by 1 foot. We can use this information to write an equation that represents the situation.

Let y be the height of the sand dune after x years. Initially, the sand dune stands 5 feet above sea level, so we can write:

y = 5

However, the sand dune erodes at a rate of 1 foot per 20 years, so for each year that passes, the height of the sand dune decreases by 1/20 feet. This means that after x years, the height of the sand dune will be:

y = 5 - (1/20)x

Therefore, the equation that represents the situation is:

y = -1/20 x + 5

So, the correct option is:

y = negative StartFraction 1 Over 20 EndFraction x + 5

Answer 2

The correct equation that represents the situation is:

y = negative StartFraction 1 Over 20 EndFraction x + 5

This equation reflects the fact that the dune is eroding at a rate of 1 foot per 20 years, so the height of the dune is decreasing as time goes on. The "-5" term in the equation represents the initial height of the dune at 5 feet above sea level.