The ratio of boys to girls in a swimming lesson is 3: 7. If there are
children in total, how many boys are there?
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Answer :

Certainly! Let's tackle this step-by-step:

1. Understand the Ratio: The ratio of boys to girls is given as 3:7. This means for every 3 boys, there are 7 girls.

2. Total Parts in the Ratio: If you add the parts of the ratio together, you get the total number of parts.
[tex]\[ 3 \text{ (boys)} + 7 \text{ (girls)} = 10 \text{ (total parts)} \][/tex]

3. Total Number of Children: It is given that there are 10 children in total in the swimming lesson.

4. Determine Number of Boys:
- Since the total number of parts in the ratio is 10, you can find out how many boys correspond to these parts:
[tex]\[ \text{Number of boys} = \left(\frac{\text{Ratio of boys}}{\text{Total parts in the ratio}}\right) \times \text{Total number of children} \][/tex]

- Substitute the values into the equation:
[tex]\[ \text{Number of boys} = \left(\frac{3}{10}\right) \times 10 \][/tex]

- Simplify the calculation:
[tex]\[ \text{Number of boys} = 3.0 \][/tex]

So, the number of boys in the swimming lesson is 3.