To determine the number of girls in the 7th grade at GACA, we can start by using the ratio of boys to girls, which is given as 2 to 4.
This means that for every 2 boys, there are 4 girls. To find the total parts in the ratio, we add the parts of boys and girls:
\[ 2 + 4 = 6 \text{ parts} \]
Next, we can calculate the total number of girls by determining how many of these parts correspond to girls. The ratio of girls is 4 parts out of the total 6 parts, so the proportion of girls is given by:
\[ \frac{4 \text{ (girls parts)}}{6 \text{ (total parts)}} = \frac{2}{3} \]
Now, to find the expected number of girls out of the total 850 students, we can set up the equation: \[ \text{Number of girls} = \text{Total students} \times \text{Proportion of girls} \] \[ \text{Number of girls} = 850 \times \frac{4}{6} \] \[ \text{Number of girls} = 850 \times \frac{2}{3} \] \[ \text{Number of girls} = \frac{1700}{3} \approx 566.67 \]
When rounding to the nearest whole number, we find: \[ \text{Number of girls} \approx 567 \]
Thus, the answers to the questions are:
Proportion to use: \( \frac{4}{6} \) or \( \frac{2}{3} \)
Expected number of girls (rounded to the nearest whole number): 567 girls out of 850 students.
1 answer