Answer:
t = 5.27 years
Explanation:
First of all, the formula for corrosion penetration rate is given as;
CPR = (KW)/(ρAt)
Where;
K = Constant dependent on exposed area A.
W - weight lost after time
t- time
ρ - density
A - exposed area
From the question;
W = 7.6kg or 7.6 x 10^(6) mg
CPR = 4 mm/yr
ρ = 4.5 g/cm³
Area = 800 cm²
K is a constant of 87.6cm
Making t the subject of the formula from the CPR equation, we obtain;
t = KW/(ρA(CPR))
t = (87.6 x 7.6 x 10^(6))/(4.5 x 800 x 4) = 46233.3 hours
The question wants the time in years.
So let's convert;
There are 8760 hours in a year.
Thus;
t = 46233.3/8760 = 5.27 years.