For 2015, we have long weekends on 7 out of the 11 public holidays, a "bumper crop", according to the Straits Times. Is this truly a long weekend bonanza, or something closer to the theoretical average?
For most public holidays, the odds of the holiday falling on Monday, Friday, or Sunday are 3/7 = 43%. However, not all holidays are the same. Firstly, there are two consecutive holidays during Chinese New Year. Because of this, the probability of getting a long weekend over Chinese New Year is higher than that for other public holidays. Secondly, Good Friday guarantees you at least one long weekend a year.
Hence, I used some combinatorics to account for different holiday permutations, and calculated the probability of getting varying numbers of long weekends a year. The results are presented in the chart below.
|Source: author's calculations|
There are 7 long weekends in 2015. The odds of this happening is not high, at 12.4% only (or once every 8 years), so it truly is a bumper crop of long weekends.