Subject: General Aptitude · Chapter: Permutations and Combinations · Exam: 2011 · Marks: · Difficulty:
There are six teachers. Out of them two are primary teachers and two are secondary teachers. They are to stand in a row, so as the primary teachers, middle teachers and secondary teachers are always in a set. The number of ways in which they can do So, is
(a)52
(b)48
(c)34
(d)None of these
Answer
Answer (as printed): B
Explanation
There are 2 primary teachers. They can stand in a row in P(2, 2) = 2! = 2 × 1 ways = 2 ways ∴ Two middle teachers. They can stand in a row in P(2, 2) = 2! = 2 × 1 = 2 ways There are two secondary teachers. They can stand in a row in P(2, 2) = 2! = 2 × 1 = 2 ways These three sets can be arranged themselves in 3! Ways = 3 × 2 × 1 = 6 ways Hence, the required number of ways = 2 × 2 × 2 × 6 = 48 ways
Explanation as extracted from the printed page; notation may be imperfect.