In a pon-leap year, total number of days is 365. Out of them, there are 52 weeks and 1 day extra. Thus, a non-leap year always has 52 Sunday. The remaining 1 day can be Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday.
Out of these 7 cases, we have Sunday in one case. ∴ Total number of outcomes =7
Number of favourable outcomes =1
Hence, required probability =71