Question

If total frequency of 3 series are 50 , 60 , 90 and their means are 12 , 15 , 20 then the mean of their composite series (combined mean) is

Answer 1

Answer:

Given frequency =120

⇒17+f1+32+f2+19=120

⇒f1+f2=52

Mean =∑fi∑xifi

⇒mean =120(10×17)+(30×f1)+(50×32)+(72×f2)+(90×19)

⇒mean =120170+30f1+1600+70f2+1710=50

⇒3f1+7f2=252

⇒3f1+7(52−f1)=252

Step-by-step explanation:

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