A study on the enhancing effect of coffee on long-term memory found that 35 participants given $200 \mathrm{mg}$ 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 $300 \mathrm{mg}$ performed better than the $200 \mathrm{mg}$ group, with a probability of $0.75$ that this difference is due to chance. What do you conclude?