21. In a particular month there were 5 Saturdays and 5 Sundays but only 4 Mondays and 4 Fridays.
What must occur in the next month?
A 5 Wednesdays
B 5 Thursdays
C 5 Fridays
D 5 Saturdays
E 5 Sundays
Solution
A

A month with 5 Saturdays and 5 Sundays but only 4 Mondays and 4 Fridays contains 30 days and ends on a Sunday. Each month in the year that contains 30 days is followed immediately by a month containing 31 days. Therefore the next month contains 31 days and starts on a Monday. Hence it will contain 5 Mondays, 5 Tuesdays and 5 Wednesdays but only 4 of the other four days.