# Ex 1.6, 5 - Chapter 1 Class 11 Sets

Last updated at July 11, 2018 by Teachoo

Last updated at July 11, 2018 by Teachoo

Transcript

Ex 1.6, 5 If X and Y are two sets such that X has 40 elements, X ∪ Y has 60 elements and X ∩ Y has 10 elements, how many elements does Y have? In this question, We are given number of elements of a set, its union, and its intersection We need to find number of elements of the other So, we put values in the formula and find the answer Let's do it Given n(X) = 40, n(X ∪ Y) = 60, n(X ∩ Y) = 10 We know that: n(X Y) = n(X) + n(Y) n(X Y) 60 = 40 + n(Y) 10 60 = 40 10 + n(Y) 60 = 30 + n(Y) n(Y) = 60 (30) n(Y) = 30 Thus, the set Y has 30 elements.

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.