To solve the problem, let's follow these steps:

Problem:

• There are 7 boys at a youth club.
• The ratio of boys to girls is $1 : 2$.

We need to find the total number of children at the youth club.

Solution:

1. Understand the ratio: The ratio $1 : 2$ means that for every 1 boy, there are 2 girls.

2. Find the multiplier: If there are 7 boys and the ratio states 1 boy corresponds to 2 girls, we can calculate the number of girls by multiplying $7$ (the boys) by $2$: $\text{Number of girls} = 7 \times 2 = 14$

3. Calculate the total number of children: Add the number of boys and girls: $\text{Total children} = \text{Number of boys} + \text{Number of girls}$ $\text{Total children} = 7 + 14 = 21$

Final Answer:

There are 21 children at the youth club in total.

Would you like further explanation or have any questions?

Related Questions:

1. If the ratio of boys to girls changes to $2 : 3$, how many girls would there be?
2. If there are 14 girls, how many boys are there based on a $1 : 2$ ratio?
3. If 3 more boys join the club, what will the new ratio of boys to girls be?
4. What percentage of the children at the club are boys?
5. How many boys would there be if the total number of children were 30 in the same ratio?

Tip:

Ratios can be scaled by multiplying or dividing both parts of the ratio equally. Always use the same multiplier for both sides of the ratio.