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Feb 9, 2014

# Find the missing frequencies in the following frequency distribution

Find the missing frequencies in the following frequency distribution if the mean is 50.25 and the total no of students in the class is 80. Marks obt.(%) 25 35 45 55 65 75 85 No. of students 7 23 x 15 10 y 5

Kishore Kumar

 Given, mean = 50.25 Sum of observations = 80 That is (60 + x + y) = 80 (x + y) = 20 … (1) Mean = (2880 + 45x + 75y)/80 That is (50.25 × 80) = 2880 + 45x + 75y 4020 – 2880 = 45x + 75y 45x + 75y = 1140 3x + 5y = 76 … (2) On solving (1) and (2), we get x =2 and y = 18

Syeda

Member since Jan 25, 2017

Answer. Given, mean = 50.25 Sum of observations = 80 That is (60 + x + y) = 80 (x + y) = 20 … (1) Mean = (2880 + 45x + 75y)/80 That is (50.25 × 80) = 2880 + 45x + 75y 4020 – 2880 = 45x + 75y 45x + 75y = 1140 3x + 5y = 76 … (2) On solving (1) and (2), we get x =2 and y = 18
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