A coin whose faces are marked 3 and 5 is tossed 4 times. The odds against the sum of the numbers thrown being less than 15 are

E<15 E¯≥15 (3  3  5  5)    (5  5  5  3)    (5  5  5  5) P(E¯)=4!2!2!+4!3!+116             =1116 P(E)=516 The odds against the sum of the numbers thrown being less than 15 are  11:5