**Question**

Teachers! Do you ever realise how
you set questions? This must be a pretty
small stadium. Or else a very sparse
one. Which stadium would allow you to
book it for its use when there are relatively so few people? Anyway, let us ignore that and get on with
the “problem”.

I am going
to illustrate my Distinguished Ratio Units method, as usual. You can use bar models if you want. There are many ways to skin the cat, as they
say.

**Solution**

We organise the given information by setting up a table. We work out that there are 560
males in total. I used “triangle”
ratio units for the adults and “circle” units for the children. You can use anything you like, as long as you
make it clear they are different.

My favorite tactic is to equalise one of
the ratio units. It is particularly easy
to use units that with the number
1. Let us multiply the left
column by 2, as shown below. Imagine what would happen if each male was
cloned to have two copies of each person.

The circle units are now equalised. This serves as a stepping stone or a bridge
to connect 2 “triangle” units with
6 “triangle” units. By comparison and subtraction, we figure out
that 4
“triangle” units correspond to
400. And we can work out the rest
easily.

**Ans:**There are 520 girls.

**Final Remarks**

Distinguished Ratio Units are easy to use. The strategy is:

(1)
use different types of units marked by differently-shaped outlines

(2) look for a unit with “1”, multiply to
equalise the unit of that type

(3) compare the other type of unit and solve that

(4) solve the rest of the problem

With this method, you do not need to worry about
drawing and redrawing bars, or cutting bars into many smaller bars. You can just concentrate on the problem
modelling and thinking.

H02. Use a
diagram / model (use an

*effective*one J)
H04. Look for
pattern(s)

H05. Work
backwards

H09. Restate
the problem in another way

H11. Solve part
of the problem

**Suitable Levels**

*****Primary School Mathematics

* other syllabuses that involve whole
numbers and ratios

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