Question

The Reading Company (TRC) develops educational products that it tries to sell to school districts all across the United States. TRC prides itself on only marketing products that have been empirically supported by research. It has developed a new product that is designed to improve the reading comprehension ability of 3rd through 6th graders. The product costs US$20,000 a year. Obviously, it will be easier to sell this product if TRC can provide potential buyers with empirical evidence that the product actually works. Their researchers took a random sample of 18 students from a school district that had a mean reading comprehension score of µ = 400 with a standard deviation of 100. The population of reading comprehension scores is normally shaped. After using the product for two semesters the mean reading comprehension scores for these 18 students was M = 443, z = 1.82, d = .43. Based on the obtained z value for the above TRC study and an α level of .05, do they have sufficient evidence to reject their null hypothesis?

a) Yes, the z score is in the critical region.

b) Yes, the z score is outside of the critical region.

c) No, the z score is in the critical region.

d) No, the z score is outside of the critical region.

Answer 1