Holly paints one garden chair in 12
minutes. Write an equation for the number of
chairs 𝑐 that she could paint in ℎ-hours.
We are told in this question that
Holly can paint one chair in 12 minutes. However, we’re interested in the
number of chairs that she can paint in ℎ-hours. Let’s firstly consider how many
chairs Holly could paint in one hour. We know that 60 minutes is equal to
one hour. We need to work out the number of
chairs that can be painted in 60 minutes.
We could begin to count up in
twelves. Holly would be able to paint two
chairs in 24 minutes as 12 plus 12 is 24. Adding another 12 gives us 36
minutes. So she can paint three chairs in
this time. Holly could paint four chairs in 48
minutes and five chairs in 60 minutes. You might however have noticed
immediately that 12 multiplied by five is equal to 60. Either way, we can see that Holly
can paint five chairs in 60 minutes or one hour.
We now need to write an equation
for the number of chairs 𝑐 that she can paint in ℎ-hours. If Holly can paint five chairs in
one hour, she could paint 10 chairs in two hours, 15 chairs in three hours, and so
on. In ℎ-hours, she would be able to
paint five ℎ or five multiplied by ℎ chairs. Our equation is therefore 𝑐 is
equal to five ℎ. We could then substitute in values
for ℎ and 𝑐. We could substitute in values for ℎ
to work out the number of chairs painted in a certain number of hours or substitute
in a value for 𝑐 to work out the number of hours it would take to paint a certain
amount of chairs.