Researchers at NASA wanted to learn the effects of spaceflight on a rat's red blood cell count (RBC). The following data represent the RBC at lift-off minus 3 days (RBC-L3) and immediately upon return (RBC-R0) of 27 rats sent to space on the Spacelab Sciences 1 flight.

They used Minitab to test whether the RBC three days prior to lift-off was different from the RBC upon return. The results are as follows:

(a) State the null and alternative hypotheses.
(b) Does it appear that the flight to space affected the RBC of the rats? Use the α = 0.05 level of significance. Support your answer.