Answer:
do not Install guard rail because the guard rail cost exceed the expected benefits
Explanation:
given data
guard rail cost = $70,000
average damage = $10,000
guard rail prevent = 5 vehicles
to find out
What should the county do
solution
we know here guard rail cost is $70,000
but expected benefits = $10,000 × 5
expected benefits = $50,000
so we can say that do not Install guard rail because the guard rail cost exceed the expected benefits