Basic Statistics20825 marksNumerical: Confidence interval for proportionConfidence interval for population proportion
A sample survey of 400 customers shows that 350 are satisfied with ABC company providing internet service. Estimate the proportion of satisfied customers in the market with 95% and 99% confidence interval.
A sample survey of 400 customers shows that 350 are satisfied with ABC company providing internet service. Estimate the proportion of satisfied customers in the market with 95% and 99% confidence interval. [5]
- Sample size: $n = 400$ - Number of satisfied customers: $x = 350$ - Confidence levels required: 95% and 99% $$\hat{p} = \frac{x}{n} = \frac{350}{400} = 0.875$$ $$\hat{q} = 1 - \hat{p} = 0.125$$ $$SE = \sqrt{\frac{\hat{p},\hat{q}}{n}} = \sqrt{\frac{0.875 \times 0.125}{400}} = \sqrt{\frac{0.1093...