In a non-leap year, the probability of having 53 Tuesdays or 53 Wednesdays is

Given a non-leap year 

$\therefore$A non leap year has 365 days 

Which includes 52 whole weeks 

$\therefore$52 X 7 = 364 

Remaining is 1 day which could be either of the day out of 7 days.

$\therefore$Probability of having 53 Tuesdays or 53 2 Wednesday $=\frac{2}{7}$