Final answer:
To find the cost of painting the inside and outside of the rectangular box, you need to calculate the surface area of the box and multiply it by the cost per unit. Using the formula for the surface area of a rectangular box, the cost can be determined.
Step-by-step explanation:
To find the cost of painting the inside and outside of the rectangular box, we first need to calculate the surface area of the box. The surface area of a rectangular box can be found by adding together the areas of all six sides.
The formula to calculate the surface area of a rectangular box is:
A = 2lw + 2lh + 2wh
Plugging in the given measurements:
A = 2(0.1*0.7) + 2(0.1*0.5) + 2(0.7*0.5)
Simplifying the equation gives:
A = 0.14 + 0.1 + 0.7
A = 0.94 cm²
Now, to find the cost of painting, we multiply the surface area by the cost per unit:
Cost = 0.94 cm² * 90 naira/cm²
Cost = 84.6 naira
Therefore, the cost of painting the inside and outside of the rectangular box at 90 naira per square centimeter is 84.6 naira.