Exams › IBPS PO › Quantitative Aptitude
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?
- 60
- 50
- 70
- 80
Correct answer: 70
Solution
From class A, boys = 50 and probability of selecting a boy is 5/12, so total students in A = 50 ÷ (5/12) = 120, hence girls in A = 70. Using the overall boys condition and the equality of probabilities for B and C, we can form equations for the unknown boys in B and C. Solving these gives boys in class C = 70.
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