|
A
recipe which serves six people uses 2 cups of sugar, 3
eggs, 1 1/2 cups of flour and a tbsp. of vanilla. If Mary
wanted to serve 8 people how many eggs would she need. |
Let's list
all of the information, and classify it as either
relevant or
irrelevant.
The recipe
serves 6 people.
Relevant
The recipe uses
2 cups of sugar.
Irrelevant
The recipe uses
3 eggs.
Relevant
The recipe uses
1 1/2 cups of flour.
Irrelevant
The recipe uses
1 tbsp. of vanilla.
Irrelevant
Mary wants to
serve 8 people.
Relevant
Once we see
what information is important (relevant)
it's easy to see how to solve the problem.
Since the
original recipe uses 3 eggs to serve 6 people, we have a ratio of 3
to 6. Simplifying that ratio (treat it as a fraction and reduce) we
see the ratio of eggs to people is 1 egg for every 2 people. Another
way of looking at the ratio is that it takes half as many eggs as
there are people. Since we are cooking for 8 people we will
need 4 eggs!
Let's look at
one more example.
|
In triangle ABC, the three
sides are 14 cm., 23 cm., and 31 cm. respectively. The
height of the triangle is 9 cm.. Find the perimeter of the
triangle. |
|
