Probability Aptitude Mcq Pdf Model Questions & Answers, Practice Test for ibps po mains 2024 2025

Answer: (d)

Total number of balls = 8. Let the first drawn ball is white, so required probability

= $5/8 × 3/7 × 4/6 × 2/5 = 1/14$

But here we had started with a white ball.

When we start with a black ball, the required probability

= $3/8 × 5/7 × 2/6 × 4/5 = 1/14$.

Since these two cases are mutually exclusive.

Total probability = $1/14 + 1/14 = 2/14 = 1/7$.

Answer: (b)

Required probability = 1/6.

Answer: (a)

In a leap year there are 366 days in which 52 weeks and two days.

The combination of 2 days may be : Sun-Mon, Mon-Tue, Tue-Wed, Wed-Thu, Thu-Fri, Fri-Sat, Sat-Sun.

P(53 Fri) = $2/7$; P (53 Sat) = $2/7$

and P (53 Fri and 53 Sat) = $1/7$

∴ P (53 Fri or Sat) = P (53 Fri) + P (53 Sat) – P (53 Fri and Sat)

= $2/7 + 2/7 - 1/7 = 3/7$

Answer: (c)

P(A) + P(B) + P(C) = 1 → 2 P(B)/3 + P(B) + P(B)/2 = 1 → 13P(B)/6 = 1 → P(B) = 6/13.

Hence, P(A) = 4/13

Answer: (b)

The probability that a man will not live 10 more years = 3/4 and the probability that his wife will not live 10 more years = 2/3.

Then the probability that neither will be alive in 10 years = 3/4 × 2/3 = 1/2