Find the cost of installing a fence around all sides of a rectangular yard that is 50 feet by 90 feet. The fence that is being used costs $8.50 per foot.
The perimeter of the rectangular yard is $50+50+90+90=<<50+50+90+90=280>>280$ feet.
The cost of installing a fence around all sides of the yard is $280*8.50=$<<280*8.5=2380>>2380. Answer: \boxed{2380}.
To find the cost of installing a fence around all sides of a rectangular yard, we need to calculate the perimeter of the yard and then multiply it by the cost per foot of the fence.
The formula to find the perimeter of a rectangle is P = 2(L + W), where P is the perimeter, L is the length, and W is the width.
Given that the length of the yard is 50 feet and the width is 90 feet, we can substitute these values into the formula:
P = 2(50 + 90)
P = 2(140)
P = 280
So, the perimeter of the yard is 280 feet.
Now, we can multiply the perimeter by the cost per foot to find the total cost of the fence:
Total Cost = Perimeter × Cost per foot
Total Cost = 280 × $8.50
Total Cost = $2380
Therefore, the cost of installing a fence around all sides of the rectangular yard is $2380.