You are building a ramp that will in the shape of a perfect right-angled triangle. the vertical height of the ramp will be 10 feet. The horizonatal base of the ramp will be 15 feet. What will be the length of the downward sloping side of the ramp?

I calculated 18 feet? Is that correct

That's correct -- or if you carry it out farther -- 18.03 feet.

To calculate the length of the downward sloping side of the ramp, we can use the Pythagorean theorem. The theorem states that in a right-angled triangle, the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.

In this case, the vertical height of the ramp is the side opposite the right angle and has a length of 10 feet. The horizontal base of the ramp is the side adjacent to the right angle and has a length of 15 feet. Let's use the Pythagorean theorem to find the length of the hypotenuse.

The equation will be:
hypotenuse^2 = height^2 + base^2

Plugging in the values we have:
hypotenuse^2 = 10^2 + 15^2
hypotenuse^2 = 100 + 225
hypotenuse^2 = 325

To find the length of the hypotenuse, we take the square root of both sides:
hypotenuse = √325

Calculating the square root of 325, we find that the length of the downward sloping side of the ramp is approximately 18.03 feet, rounded to two decimal places.

So, it seems that your calculation of 18 feet is quite close. The correct length is approximately 18.03 feet.