A number is chosen at random among the first 120 natural numbers. The probability of the number chosen being a multiple of 5 or 15 is?

Probability of getting head in one trail = 1/2
? Reqd Probability of getting heads in both the trails = 1/2 x 1/2 = 1/4

Number of cases favourable of E = 3
Total Number of cases = (3 + 5 ) = 8
? P(E) = 3/8

P (getting a prize ) = 20 / (20 + 15 ) = 20 / 35 = 4/7

P (red) = 9 / (9 + 7 + 4) = 9/20
? P(not-red) = (1 - 9/20) = 11/20

S = {1, 2, 3, ......16}
E = {2, 3, 5, 7, 11, 13}
? P(E) = n(E)/n(S) = 6/16= 3/8

No of white balls = 7
Red balls = 9
Total no. of balls = 7 + 9 = 16
Probability of drawing a white ball = 7/16

Total ways = 52
There is one queen of club and one king of heart favourable ways = 1 + 1 = 2.
? Required probability = 2/52 = 1/26

Here, n(5) = {a, e, i,o, u}
and E = Event of selecting the vowel i = {i}
? P(E)= n(E)/n(S) = 1/5

Required probability = P(A) x P(B)
= (7/8) x (9/10)
= 63/80

Total number of letters = n(S) = 11
whereas, number of vowels = n(E) = 4
? Required probability = n(E)/n(s) = 4/11