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.

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Rat RBC-L3 RBC-RO Rat RBC-L3 RBC-RO 112 7.53 8.16 79 7.79 8.52 145 7.79 9.15 47 8.24 8.59 15 7.84 9.09 109 7.69 7.29 6,86 142 8.42 13 7.23 8.93 8.96 45 7.93 74 7.83 8.64 150 7.48 9.25 126 8.09 9.65 162 7.94 7.40 157 8.27 8.76 136 7.95 9.55 156 7.27 9.11 8.23 127 8.44 9.38 128 9.81 9.66 153 6.70 99 14.50 9.86 97 6.95 8.83 90 7.73 9.90 94 6.73 8.46 82 7.31 7.64 124 7.21 9.04 55 7.84 9.54 6.95 117 9.48 Wilcoxon Signed-Rank Test Test of median = 0.000000 versus median not = 0.000000 N for Test 27 Wilcoxon statistic 343.0 Estimated Median 1.255 differen 27 0.000 1.255