Should I use “was” or “were”? [duplicate]

Question

One of the successful managers were asked

or

One of the successful managers was asked

Answer 1

Purdue OWL has this example which is almost identical to OP's case:

One of the boxes is open.

The verb agrees with the subject, "One". If you wanted to talk about "two", you would use a plural verb:

Two of the successful managers were asked.

One of the successful managers was asked.