The weight of organic apples in a grocery store follows a normal distribution with a mean of 150 g and a standard deviation of 12 g.
Find the probability that a randomly selected apple weighs more than 165 g.
Write down a null and alternative hypothesis for a two-tailed test.
A farmer takes a sample of 15 apples and finds a mean weight of 158 g. Test at the 5% significance level whether there is evidence that the mean weight of apples has changed.