A bag contains balls numbered from 1 to 42. One ball is drawn at random from these balls. The probability that its number is a multiple of 7 or 8 is:
11⁄42
Numbers from 1 to 42 that are multiples of 7: {7, 14, 21, 28, 35, 42} → 6 numbers Numbers that are multiples of 8: {8, 16, 24, 32, 40} → 5 numbers Numbers that are multiples of both 7 and 8 (LCM = 56, but 56 is not in range) → 0 numbers Using the formula for union in probability: P(A ∪ B) = P(A) + P(B) - P(A ∩ B) = (6/42) + (5/42) - (0/42) = 11/42
Important Questions from Probability
The probability of being 53 Sundays in year 2020 is-
Three dice are thrown randomly. The probability of coming 3 in at least one die is
The probability of having 53 Tuesdays in an ordinary year is:
When two dice are tossed simultaneously, the probability that the sum of the numbers appearing on both the dice is 8 will be
How many 3 - digit numbers can be formed from the digits 2, 3, 5, 6, 7 and 9, which are divisible by 5 and none of the digits is repeated?
