Final answer:
The subject is Mathematics at the High School level. A 90 percent confidence interval for the true proportion of students against the new school uniform legislation is calculated using the sample proportion and the standard error, multiplied by the z-score for the desired confidence level.
Step-by-step explanation:
The survey conducted by the student at her school regarding the new legislation on school uniforms involves the subject of Mathematics, specifically statistics. To calculate a 90 percent confidence interval for the true percentage of students who are against the new legislation, you can use the formula for a confidence interval for a population proportion.
The student found that 480 out of 600 students are against the new legislation. This means that the sample proportion (p) is 480/600 = 0.8 or 80%. To compute the confidence interval, use the following steps:
- Find the standard error (SE) of the sample proportion, which is the square root of (p*(1-p)/n), where p is the sample proportion and n is the sample size.
- Find the z-score corresponding to the desired confidence level (90%). You can find this value in a standard z-table.
- Multiply the z-score by the SE to determine the margin of error (ME).
- Add and subtract the ME from the sample proportion to find the lower and upper bounds of the confidence interval.
Interpreting the confidence interval means that we can be 90% confident that the true proportion of students who are against the new legislation lies within the calculated interval.