7. 2
a)
An open rectangular box measuring 28 cm by 20 cm
by 12 cm internally is made of woodcm thick. Find:
the capacity of the box in litres,
the volume of wood used in making the box,
the mass of the box if the density of the wood used is
1.25 g/cm3
b)
c)
J
28 82

1. Capacity of the box in Litres: 7.917L≈8L

2. Volume of wood used in making the box: 1197cm^3

3. The mass of the box: 1496.25g/cm^3

Step-by-step explanation:

1. 29×21×13=7917cm^3

7917cm^3 → 7.917dm^3→7.917L≈8L

2. Outside Volume: 29×21×13=7917cm^3

Inside Volume: 28×20×13=6720cm^3

7917-6720=1197cm^3

3. 1197×1.25=1496.25g/cm^3

rectangle: 9 1/8 x 4 1/9 = 37 37/72in

parallelogram: b times h= 10.3 x 6.2 = 63.86

trapezoid: a+b/2 times h= 42.5

volume of prism: l times w times h= 36