Difference of Two Means (Setup) Practice Test

A researcher is comparing mean reaction time (in milliseconds) between people who drank caffeinated coffee and people who drank decaf. A random sample of 36 caffeinated participants had a mean reaction time of 240 ms, and a random sample of 34 decaf participants had a mean reaction time of 255 ms. The research claim is that caffeine reduces mean reaction time. Which hypotheses are appropriate?

A nutritionist compares the mean LDL cholesterol level (mg/dL) for adults following a Mediterranean diet versus adults following their usual diet. A sample of $n=32$ Mediterranean-diet adults had a mean LDL of $\bar{x}=112.3$, and a sample of $n=30$ usual-diet adults had a mean LDL of $\bar{x}=119.7$. The nutritionist claims the Mediterranean diet reduces the population mean LDL level. Which hypotheses are appropriate?