Consider the following premises. There is at least one z for which if z were a musician, then z is playing squash. For all z, z will work if and only if z will play squash. For all z, if z plays squash, then z is a musician. Can we infer the following from them? There is at least one z for which if z were a musician, then z is working.
 From the fact that there is at least one z for which if z were a musician, then z is playing squash, and that for all z, if z plays squash, then z is a musician we can infer that there is at least one z for which z is a musician if and only if z will play squash. From the fact that there is at least one z for which z is a musician if and only if z will play squash we can infer that there is at least one z for which if z were a musician, then z is playing squash. From the fact that for all z, z will work if and only if z will play squash we can infer that for all z, if z plays squash, then z is working. Finally, from the fact that there is at least one z for which if z were a musician, then z is playing squash, and that for all z, if z plays squash, then z is working we can infer that there is at least one z for which if z were a musician, then z is working. Therefore, the answer is yes.