Answer:
The value is

Explanation:
From the question we are told that
The capacity of the metal tank is

The duration usage is

The cost of 2000-gallon tank 15 years ago is

The capacity of the second tank considered is
The power sizing exponent is

The initial construction cost index is

The new construction after 15 years cost index is

Equation for the power sizing exponent is mathematically represented as
![(P_n)/(P) = [(C_1)/(C) ]^(e)](https://img.qammunity.org/2021/formulas/mathematics/high-school/wp5fq79b0km457g4wbv1r1saxoo9ro29te.png)
=> Here
is the cost of 5,000-gallon tank as at 15 years ago
So
![P_n = [(5000)/(2000) ] ^(0.57) * 100000](https://img.qammunity.org/2021/formulas/mathematics/high-school/6jmvjaa8tuayclj83w9z6554udz24hm51j.png)

Equation for the cost index exponent is mathematically represented as

Here
is the cost of 5,000-gallon tank today
So

=>

=>
