In: Statistics and Probability
A business school claims that students who complete a 3-month typing course can type a mean of more than 1200 words an hour. A random sample of 25 students who completed this course typed a mean of 1163 words an hour, with a sample standard deviation of 87 words. Assume that typing speeds for all students who complete this course have an approximately normal distribution. (a) Using the critical value method and a significance level of 1%, is there evidence to support the business school’s claim? (b) What would a Type II error be in this case?
A peony plant with red petals was crossed with another plant having streaky petals. A geneticist states that 70% of the offspring resulting from this cross will have red flowers. To test this, 80 seeds from this cross were collected and germinated and 46 plants had red petals. (a) Is there sufficient evidence at the 0.02 significance level to indicate the proportion of the hybrid plants with red petals differs from 70%? Use the P-value method in your test. (b) What would a Type I error be in this case?