Help whith a math/science problem?How would I solve this?

Question

A carpenter intends to build a storage box made of oak to the dimensions of 1m x 0.3m x 0.5M. A 10 cm thick oak plank costs 6.39 per meter ad each plank in 2.5metres in length. The density of the oak is 800 kg/m3.

a)how much does the wood cost ?(6 sided box)
b)How heavy is the box?
c) How man boards must be purchased?

Answer 1

The area of the sides are 1 x 0.3 + 1 x 0.3 + 1 x 0.5 +1 x 0.5 +0.5 x 0.3 +0.5 x 0.3 = .3 + .3 + .5 + .5 + .15 + .15 = 1.9 msq

needs 19 m x 10 cm

Cost = 19 x 6.39 = 121.41

? no idea

7 3/4

Answer 2

sorry I dont do math good luck!