A proposed null hypothesis states that there is no difference in the population mean heights of two neighboring districts. The d
ifference of the sample means is 10 cm, and the standard deviation of the difference of sample means is 6 cm. Which conclusion can we draw at the 68% confidence level?
That there is in fact a difference, you should reject the null. 10cm is outside of one standard deviation which is what corresponds to a 68% confidence level
Null hypothesis is something that states that there is no difference between the population means, while the alternative hypothesis states that there is difference between the two.
So, If the difference of the sample means is 10cm, and the standard deviation of the difference of sample means is 6 cm. Then the population means of the two districts will be different according to the manual solution.