An open no top rectangular box with length 600 ft width 400

An open (no top) rectangular box with length 6.00 ft, width 4.00 ft, and height 2.25 ft is to be painted on all interior and exterior sides, including the bottom, with a waterproof material. Each gallon covers 11.0 ft^2 and costs $40. a. Find how many gallon containers must be purchased and the cost of painting this box. b. If the box is 4/5 full of water, find the weight of the water. (Water weighs 62.4 lb/ft^3.)

Solution

Rectangular open box : Total surface area = 2( l*w +l*h + b*h )

= 2( 6*4 + 6*2.25 + 4*2.25) = 93 sq foot

a) each gallon = 11 ft^2

So, no. of gallons = 93/11 = 8.45

Cost = 8.45*40 = $ 338.18

b) volume of water = (l*w*h)(4/5) = 43.2 ft^3

Weight of water = 62.4*43.2 = 2695.68 lb