1 year = 365 days
A leap year has 366 days
A year has 52 weeks. Hence there will be 52 Thursdays for sure.
52 weeks = 52 x 7 = 364 days
366 – 364 =2 days
In a leap year there will be 52 Thursdays and 2 days will be left.
These 2 days can be:
Sunday, Monday
Monday, Tuesday
Tuesday, Wednesday
Wednesday, Thursday
Thursday, Friday
Friday, Saturday
Saturday, Sunday
Of these total 7 outcomes, the favourable outcomes are 2.
Hence the probability of getting 53 Thursday in a leap year = 2/7.