We know that,

Probability of occurrence of an event

An ordinary year has 365 days i.e. it has 52 weeks + 1 day. So, there will be 52 Tuesdays for sure(because every week has 1 Tuesday)

So, we want another Tuesday that to from that 1 day left(as there is only one Tuesday left after 52 weeks)
This one day can be, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday.
Of these total 7 outcomes, the desired outcome is 1, i.e. Tuesday

Therefore, the probability of getting 52 Tuesdays in an ordinary year

Conclusion: Probability of getting 53 Tuesdays in an ordinary year is