A leap year has 366 days with 52 weeks and 2 days.

Now, 52 weeks contains 52 Sundays.

The remaining two days can be:(i) Sunday and Monday, (ii) Monday and Tuesday, (iii) Tuesday and Wednesday, (iv) Wednesday and Thursday, (v) Thursday and Friday, (vi) Friday and Saturday,

(vii) Saturday and Sunday

Let E be the event of getting a leap year with 53 Sundays

Number of favourable cases is: 2

∴ P (a leap year having 53 Sundays) = P (E) = 2/7