Class 11 Maths Chapter 2: Relations and Functions case study question with answers
One case-based question of the kind CBSE-pattern school exams ask: a passage, then 3 parts worth 4 marks in all, with the answer and the marking scheme for each. Written from the NCERT chapter.
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Answer: (b) 6
n(S × D) = n(S) × n(D) = 3 × 2 = 6.
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Answer: (c) (lassi, idli)
In S × D the first element is a snack and the second a drink; (lassi, idli) has them the wrong way round, and order matters.
Answer and marking scheme
Domain = {samosa, idli, poha}, range = {tea, lassi}. M is not a function: idli has two images, lassi and tea.
- domain {samosa, idli, poha} and range {tea, lassi} (1)
- not a function, as idli has two images (1)
Answer and marking scheme
M fails to be a function only because idli has two images, so one of (idli, lassi) and (idli, tea) must go; removing any other pair leaves an element of S with no image. Removing (idli, lassi) leaves {(samosa, tea), (poha, tea), (idli, tea)}, range {tea}. Removing (idli, tea) leaves {(samosa, tea), (idli, lassi), (poha, tea)}, range {tea, lassi}.
- (idli, lassi) or (idli, tea), with the reason (1)
- ranges {tea} and {tea, lassi} (1)