Exams › IBPS PO › Quantitative Aptitude

A bag has 15 red, green and blue balls. Number of each balls is different in the bag. Difference between red ball and green ball is same as difference between green ball and blue ball. Probability of selecting one blue ball from the bag is greater than 0.2, then number of blue balls in the bag can be (A) 3 (B) 4 (C) 5 (D) 7 (E) 9

1. Only B, C, D and E
2. Only B, D, E
3. All A, B, C, D and E
4. Only C, D, E

Correct answer: Only B, D, E

Solution

G is the arithmetic mean: G=5 always. R+B=10, all different (R≠B≠5). P(blue)>0.2 → B/15>0.2 → B>3. Option A(3): B=3≤3 ✗. Option B(4): B=4>3, R=6≠5 ✓. Option C(5): B=5=G, not all different ✗. Option D(7): B=7>3, R=3≠5 ✓. Option E(9): B=9>3, R=1≠5 ✓. Valid: B, D, E. Note: original answer 'Only C, D, E' is incorrect — B=5 violates 'all different'.

Related IBPS PO Quantitative Aptitude questions

• In a bag, there are 3 magenta balls, 5 green balls, and 7 blue balls. Two balls are drawn one by one without replacement. If the first ball drawn is magenta, then 8 more magenta balls are added to the bag. Find the probability that both balls drawn are magenta.
• Q84. A box contains 4 red balls, 6 white balls, 2 orange balls, and 8 black balls. Quantity I: Two balls are drawn at random. Probability that both are either red or white. Quantity II: Three balls are drawn. Probability that all are different.
• Directions (71-72): Given below is the number of male and female students in classes A, B and C. Some data are missing, which you have to calculate as per the instructions provided. Class A | Class B | Class C Boys: 50 | -- | -- Girls: -- | 80 | 60 Note: (i) The probability of selecting a boy from class A is \(\frac{5}{12}\). (ii) The probability of selecting a boy from all the boys of all classes is \(\frac{14}{19}\), such that the boy selected is either from class B or class C. (iii) The probability of selecting a boy from class B is equal to the probability of selecting a boy from class C. How many boys are there in class C?
• A bag contains some green balls, some blue balls, and seven red balls. The probability of picking one green ball is \(\frac{1}{7}\) more than that of picking one red ball from the bag, and the probability of picking one blue ball is \(\frac{9}{35}\) more than that of picking one red ball from the bag. Find the total number of blue balls in the bag.
• Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?
• A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

⚔️ Practice IBPS PO Quantitative Aptitude free + battle 1v1 →