Question

Performing a study on the development of body height, a student randomly measures the height of 30 persons in country A. The results turn out to be: {1.7, 1.6, 1.8, 1.9, 1.75, 1.83, 1.82, 1.65, 1.95, 1.69, 1.82, 1.87, 1.65, 1.54, 1.98, 1.78, 1.69, 1.75, 1.62, 1.64, 1.75, 1.8, 1.65, 1.7, 1.82, 1.62, 1.83, 1.75, 1.7, 1.65}. In the literature, a result is found that 10 years before, the average height of persons in country A was determined to be 1.73 and standard deviation is 0.2 .

Given that the acceptable threshold for significance is 5%, can this data be used to show that the average height of individuals in country A has increased in the last 10 years?
(Show your calculations).

Answer 1

Here we have: x = 1.743 0 = 0.2 n = 30 a = 0.05 Hypothesis: Hoiul = 1.73 Hau > 1.73 Test statistics: z-distribution (o known) X- U 2=-*= 174371,73 = 0.36 1.743-1.73 0.2 V30 36

Critical value: Zcrit= Za = 20.05 = 1.645 Fail to reject the null hypothesis. Conclusion: Here we have not sufficient evidence to reject the null hypothesis.z-observed value is not greater than z-critical value. We can say that the average height of individuals in country A has not increased in the last 10 years