CBSE Class 10 Sample Paper for 2023 Boards - Maths Standard
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CBSE Class 10 Sample Paper for 2023 Boards - Maths Standard
Last updated at December 13, 2024 by Teachoo
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Transcript
Question 37 (ii) ā Choice 1 For 1500 seats in the auditorium, how many rows need to be there? Since Total seats = 1500 Given Sn = 1500, We need to find number of rows, i.e., we need to find n Now Sn = š/2 (2a + (n ā 1)d) Putting Sn = 1500, a = 30, d = 10 1500 = š/š (2 Ć 30 + (n ā 1) Ć 10) 1500 Ć 2 = n (60 + 10(n ā 1)) 3000 = n (60 + 10n ā 10) 3000 = n (50 + 10n) 3000 = 50n + 10n2 0 = 10n2 + 50n ā 3000 10n2 + 50n ā 3000 = 0 10(n2 + 5n ā 300) = 0 n2 + 5n ā 300 = 0 Solving by Splitting the middle term n2 + 20n ā 15n ā 300 = 0 n(n + 20) ā 15(n + 20) = 0 (n ā 15) (n + 20) = 0 ā“ n = 15, n = ā20 Since n cannot be negative So, n = 15 Thus, number of rows is 15
