In leap year =52 weeks +2 daysSo there are 52 sundays sure in any year, and 53th sunday depends on remaining two days.Two days may be, (M, Tu), (Tu, W), (W, Th), (Th, F), (F, Sat) ,(Sat, Sun), (Sun, M)Out of these 7 cases, sunday occurs only in 2 cases.Required probability of getting 53 sundays =total casesfavourable cases​=72​