Answer :


It is given that, mean = 50


= 50


= 50


3480 + 30f1 + 70f2 = 50 (120)


30f1 + 70f2 = 6000 – 3480


10 (3f1 + 7f2) = 10 (252)


3f1 + 7f2 = 252 (i) [Dividing by 10]


And N = 120


17 + f1 + 32 + f2 + 19 = 120


68 + f1 + f2 = 120


f1 + f2 = 52


Multiplying by ‘3’ on both sides, we get


3f1 + 3f2 = 156 (ii)


Subtracting (ii) from (i), we get


3f1 + 7f2 – 3f1 – 3f2 = 252 – 156


4f2 = 96


f2 =


= 24


Put value of f2 in (i), we get


3f1 + 7 * 24 = 252


3f1 = 252 – 168


3f1 = 84


f1 =


= 28


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