Question
Janna has some 50 cents coins. If she spends $2.50 each day, she
will have 3 coins left. If she spends $4 each day, she'll have 7
coins left. What is the minimum amount of money that she
has?
Steps to solve question 2 using the model drawing
method.
1. $2.50 = Five 50-cent
coins $1.50 = Three 50-cent
coins
$4 = Eight 50-cent
coins $3.50 =
Seven 50-cent coins
2. Since the amount of the money must be the same for both
cases, we will draw two equal length bars.
3. First
Bar : 5 : 3
:
:
Second
Bar : 8
:
7 :
:
4. Next, we will add 8 into the empty space in the
second bar
First Bar
: 5 : 3
:
:
Second
Bar : 8
:
7 : 8
:
5 7 + 8 = 15
since 15 can be divided by 5, we will
not add more 8s into the empty space in the second bar.
6. Hence,
First
Bar : 5 : 3
: 5 : 5 :
5
:
Second
Bar : 8
:
7 : 8
:
7. So, the minimum amount of money she has = (8 + 7 +
8)coins x 50 cents
= $11.50
Alternatively, the minimum amount
of money she has
= (5 + 3 + 5 + 5 + 5) coins x 50 cents
= $11.50