The mean of the following distribution is 50. Find the value of a and the frequencies of 30 and 70
X 10 30 50 70 90
f 17 5a+3 32 7a-11 19
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X=10,30,50,70,90=
f=17,5a,3,32,7a-11,19=68+12a-8
xi×fi=170+150a+90+1600+490a_770+1710=3480+640a-680
=2800+640a.
now,mean=2800+640a/68+12a-8
50=2800+640a/68+12a-8
now,doing cross multiplication.
50×(68+12a-8)=2800+640a
2800+640a=3400+600a-400
40a=200
a=200/40=5
f=17,5a,3,32,7a-11,19=68+12a-8
xi×fi=170+150a+90+1600+490a_770+1710=3480+640a-680
=2800+640a.
now,mean=2800+640a/68+12a-8
50=2800+640a/68+12a-8
now,doing cross multiplication.
50×(68+12a-8)=2800+640a
2800+640a=3400+600a-400
40a=200
a=200/40=5
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