Question:
What is the probability that an ordinary year has 53 Sundays?
Solution:
GIVEN: An ordinary year
TO FIND: Probability that a non leap year has 53 Sundays.
Total number of days in an ordinary year is 365days
Hence number of weeks in an ordinary year is 
In an ordinary year we have 52 complete weeks and 1 day which can be any day of the week i.e. SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY and SATURDAY
To make 53 Sundays the additional day should be Sunday
Hence total number of days is 7
Favorable day I.e. Sunday is 1
We know that PROBABILITY = 
Hence probability that an ordinary year has 53 Sundays is equal to