Consider the following premises. There is at least one x_7 for which x_7 will cook. For all x_7, if x_7 cooks, then x_7 is a scientist. For all x_7, x_7 will play tennis if and only if x_7 is a scientist. Can we infer the following from them? There is at least one x_7 for which x_7 will play tennis.
 From the fact that for all x_7, if x_7 cooks, then x_7 is a scientist, and that there is at least one x_7 for which x_7 will cook we can infer that there is at least one x_7 for which x_7 is a scientist. From the fact that for all x_7, x_7 will play tennis if and only if x_7 is a scientist we can infer that for all x_7, if x_7 were a scientist, then x_7 is playing tennis. Finally, from the fact that for all x_7, if x_7 were a scientist, then x_7 is playing tennis, and that there is at least one x_7 for which x_7 is a scientist we can infer that there is at least one x_7 for which x_7 will play tennis. Therefore, the answer is yes.