Question

Noah bought 15 baseball cards for $9 assuming each baseball card cost the same amount answer the following questions one at this rate how much will the third 30 baseball cards cost explain your reasoning. At this rate how much will 12 baseball cards cost explain your reasoning. Do you think this information will be better represented using a table or a double number line explain your reasoning.

Answer 1

We know that 15 baseball costs $9.

We have to divide to find the unit cost.

$\frac{9}{15}=0.6$

Each baseball card cost 60 cents.

So, for 30 cards, it would cost

$\begin{gathered} 0.6\cdot30=18 \\ 0.6\cdot12=7.2 \end{gathered}$

Hence, 30 baseball cards cost $18, at the same unit price. And 12 baseball cards would cost $7.20.

Observe that to get the answers, we just had to multiply the number of cards by the unit price.

There's no need for a table or a number double line because they are used when the amount of data is big enough. It is better to keep it simple.