A scientist was asked to test the effect of a new vitamin for rats. His hypothesis was that young rats that had vitamins added to their food would gain weight faster than young rats fed a normal diet. He predicted that if young rats were fed vitamins, then they would gain more weight by the end of the experiment. He tested the effect of adding vitamins to some of the rats'
diet by measuring the amount of weight each rat gained after three months. He then determined the average weight gained in each group. To analyze his results, he put the data he collected into the table shown below.