Consider the following premises. For all x_4, x_4 will not take a plane. There is at least one x_4 for which x_4 is a scientist. For all x_4, x_4 is not a scientist or x_4 will climb a mountain. Can we infer the following from them? There is at least one x_4 for which x_4 will climb a mountain.
 From the fact that there is at least one x_4 for which x_4 is a scientist we can infer that there is at least one x_4 for which x_4 is a scientist or x_4 will take a plane. From the fact that there is at least one x_4 for which x_4 is a scientist or x_4 will take a plane, and that for all x_4, x_4 is not a scientist or x_4 will climb a mountain we can infer that there is at least one x_4 for which x_4 will take a plane or x_4 will climb a mountain. Finally, from the fact that there is at least one x_4 for which x_4 will take a plane or x_4 will climb a mountain, and that for all x_4, x_4 will not take a plane we can infer that there is at least one x_4 for which x_4 will climb a mountain. Therefore, the answer is yes.