Step-by-step explanation:
The easiest approach is to realise that one hour is 3 times longer than
20
minutes. The longer the time, the more they will pave.
2
15
of a mile, in 20 minutes, how much in 60 minutes?#
They will pave 3 times more.
2
15
×
3
1
=
6
15
of a mile
6
15
=
2
5
of a mile
You could also use the 'unitary method' where you find out how much they pave in ONE minute (divide by
20
) and them multiply by
60
to find how much in one hour.
Look at what happens:
2
15
÷
20
×
60
=
2
15
×
1
20
×
60
3
=
2
15
×
3
←
exactly the same maths.
=
2
5
The surface area is made up of six sides and the area is then just the sum of the areas of the six sides...
A=2xy+2xz+2yz
A=2(xy+xz+yz) in this case:
A=2(5*4.5+5*3.5+4.5*3.5)
A=2(22.5+17.5+15.75)
A=2(55.75)
A=111.5 in^2
