# Find the missing

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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