Chapter 4.1, Problem 39BSC

Using Probability to Form Conclusions. In Exercises 37-40, use the given probability value to determine whether the sample results could easily occur by chance, then form a conclusion.

39. Coffee Talk A study on the enhancing effect of coffee on long-term memory found that 35 participants given 200 mg of caffeine performed better on a memory test 24 hours later compared to the placebo group that received no caffeine.

a. There was a probability of 0.049 that the difference between the coffee group and the placebo group was due to chance. What do you conclude?

b. A group given a higher dose of 300 mg performed better than the 200 mg group, with a probability of 0.75 that this difference is due to chance. What do you conclude?