Last updated at May 29, 2018 by Teachoo

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Ex 15.1, 25 Which of the following arguments are correct and which are not correct? Give reasons for your answer. (i) If two coins are tossed simultaneously, there are three possible outcomes, two heads, two tails or one of each. For each of these outcomes, the probability is 1/3 Total possible outcomes = (H, H) , (H, T), (T, H), (T, T) Number of possible outcomes = 4 Probability of getting two heads = (๐๐ข๐๐๐๐ ๐๐ ๐ก๐๐๐๐ ๐ก๐ค๐ โ๐๐๐๐ ๐๐๐๐ข๐๐ )/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐๐ข๐ก๐๐๐๐๐ ) Probability of getting two tails = (๐๐ข๐๐๐๐ ๐๐ ๐ก๐๐๐๐ ๐ก๐ค๐ ๐ก๐๐๐๐ ๐๐๐๐ข๐๐ )/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐๐ข๐ก๐๐๐๐๐ ) Probability of getting one head & one tails = (๐๐ข๐๐๐๐ ๐๐ ๐ก๐๐๐๐ ๐๐๐ โ๐๐๐ ๐๐๐ ๐๐๐ ๐ก๐๐๐ ๐๐๐๐ข๐๐ )/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐๐ข๐ก๐๐๐๐๐ ) = 2/4 = 1/2 Therefore the given statement is incorrect. The probabilities of these outcomes is not 1/3 Ex 15.1, 25 Which of the following arguments are correct and which are not correct? Give reasons for your answer. (ii) If a die is thrown, there are two possible outcomes- an odd number or an even number .Therefore the probability of getting an odd number is 1/2 Total outcomes that can occur are 1, 2, 3, 4, 5, 6 Number of possible outcomes of a dice = 6 Numbers which are odd = 1, 3, 5 Total numbers which are odd = 3 Numbers which are even = 2, 4, 6 Total numbers which are even = 3 Probability of getting an odd number = (๐๐ข๐๐๐๐ ๐๐ ๐๐ข๐ก๐๐๐๐๐ ๐คโ๐๐๐ ๐กโ๐๐๐ ๐๐ ๐๐ ๐๐๐ ๐๐ข๐๐๐๐)/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐๐ข๐ก๐๐๐๐๐ ) = 3/6 = 1/2 Hence, the given statement is correct

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About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.