Question

A bag has red and blue marbles in a 7:5 ratio. If the bag has 72 marbles total, how many are blue?



(1 point)
Responses

6 blue marbles
6 blue marbles

42 blue marbles
42 blue marbles

12 blue marbles
12 blue marbles

30 blue marbles
30 blue marbles

Answer 1

To find out how many blue marbles are in the bag, we can first determine the total number of parts represented by the ratio of red to blue marbles. The ratio of red to blue is 7:5, which means there are:

- 7 parts red
- 5 parts blue

Adding these parts together gives us:

\[
7 + 5 = 12 \text{ total parts}
\]

To find the value of each part, we divide the total number of marbles by the total parts:

\[
\text{Value of each part} = \frac{72 \text{ marbles}}{12 \text{ parts}} = 6 \text{ marbles per part}
\]

Now we can calculate the number of blue marbles:

\[
\text{Number of blue marbles} = 5 \text{ parts} \times 6 \text{ marbles per part} = 30 \text{ blue marbles}
\]

So the bag contains **30 blue marbles**.

The correct response is:

**30 blue marbles**.