Consider the following premises. For all y, if y were rich, then y is a musician. For all y, y is an office clerk if and only if y is a musician. For all y, if y were a musician, then y is rich. For all y, y is not an office clerk. Can we infer the following from them? There is at least one y for which y is rich.
 From the fact that for all y, y is an office clerk if and only if y is a musician we can infer that for all y, if y were a musician, then y is an office clerk. From the fact that for all y, if y were a musician, then y is an office clerk, and that for all y, y is not an office clerk we can infer that for all y, y is not a musician. From the fact that for all y, if y were a musician, then y is rich, and that for all y, if y were rich, then y is a musician we can infer that for all y, y is a musician if and only if y is rich. Finally, from the fact that for all y, y is a musician if and only if y is rich, and that for all y, y is not a musician we can infer that for all y, y is not rich, which contradicts that There is at least one y for which y is rich. Therefore, the answer is no.