Question 1102166
Well, assuming the thirty day month starts on a Sunday, there will be four Sundays.

When you say every other Sunday, you are skipping one sunday, then volunteering one sunday, then skipping one sunday, then volunteering on sunday. You are volunteering for 2/4 sundays, or 1/2.

How about skipping every third Sunday? You skip one Sunday, then skip again, then volunteer. Here, you Volunteer for 1/3 Sunday.

When you volunteer for every fifth sunday, you will have a 1/5 chance of going to volunteer per sunday, or per week.

We can write this as a ratio.

{{{((1/5) chance of volunteering) / (Per 1 Week)}}}

But we have four weeks, or four sundays in a month, so we multiply the numerator and the denominator by four and obtain.

{{{((4/5) chance of volunteering) / (Per 4 weeks)}}}

Your provability is 4/5 chance of volunteering for any given month.