The Islamic calendar is lunar. The beginning and ending of the calendar are determined by the sighting of the crescent moon (new moon). Muslims are supposed to sight the crescent everywhere they live. It is a purely lunar calendar, having 12 lunar months in a year of about 354 (12 x 29.53=354.36) days, so the months rotate backward through the seasons and are not fixed to the Gregorian calendar. Muslims around the globe fast during the month of Ramadan (the ninth month) and after completing the fast and sighting the new moon, the next day they celebrate an event called Eid-ul-fitre. The moon may appear either on the 29th or 30th day of the month. However, 60% of Mus- lims believe that the new moon will be sighted on the 29th day of Ramadan, and so the fasting will be completed in 29 days. What is the probability that the moon will not be sighted on the 29th day of the month?