Need a bit of help with some interpretation

Hi Reddit,

I'm currently writing up a case for my accounting course, and I'm having some difficulty with one part.

The case is about a company who is planning a conference. Currently, 15 people registered. It is one month from the date of the conference. The company has determined that at least 75% of all registrations are received a month before the conference. How many people attend the conference?

Based on my interpretation "a month" could mean within the month, or by the month. If it means by the month, 15 people represent 75% of the attendees; therefore, the total number of registrants is 20. If it means within the month, then 15 people represent 25% of the attendees, and another 75%, or 45 more people register; therefore 60 people attend under this option.

Which of the two scenarios do you believe the initial statement represents?