Success Rate Test
1. **State the problem:** We want to test if the new exercises have a higher success rate than the traditional method, which has a success rate of 70% (or 0.7).
2. **Set up hypotheses:**
- Null hypothesis $H_0$: $p = 0.7$ (new exercises are not better)
- Alternative hypothesis $H_a$: $p > 0.7$ (new exercises are better)
3. **Identify the sample data:**
- Sample size $n = 30$
- Number of successes $x = 26$
- Sample proportion $\hat{p} = \frac{26}{30} = 0.8667$
4. **Use the test statistic for a proportion:**
$$ z = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0(1-p_0)}{n}}} $$
where $p_0 = 0.7$ is the hypothesized proportion.
5. **Calculate the standard error:**
$$ SE = \sqrt{\frac{0.7 \times 0.3}{30}} = \sqrt{\frac{0.21}{30}} = \sqrt{0.007} \approx 0.0837 $$
6. **Calculate the z-score:**
$$ z = \frac{0.8667 - 0.7}{0.0837} = \frac{0.1667}{0.0837} \approx 1.99 $$
7. **Find the critical value:**
At a 5% significance level for a one-tailed test, the critical z-value is approximately 1.645.
8. **Make a decision:**
Since $z = 1.99 > 1.645$, we reject the null hypothesis.
9. **Conclusion:**
There is sufficient evidence at the 5% significance level to conclude that the new exercises have a higher success rate than the traditional method.