Final Answer:
(1) t-critical: ±2.110; (2) t-observed = -1.334 (calculated using sample mean and standard deviation); (3) The sample is not significantly different from the population.
Step-by-step explanation:
To assess if the sample perceives the natural sweetener differently than the population, we perform a t-test. The t-critical values at a two-tailed alpha of 0.05 with 17 degrees of freedom (18 participants - 1) are approximately ±2.110.
The t-observed is calculated using the sample mean, sample standard deviation, and sample size. In this scenario, it is -1.334. Since -1.334 falls within the range of ±2.110, we fail to reject the null hypothesis. The sample is not significantly different from the population mean.
This indicates that there is not enough evidence to suggest that the 18 participants who had stevia perceive it differently than the population average.