Mean, x=6a+b+68+44+48+60=55
⇒a+b+220=330
⇒a+b=110...(i)
Variance, σ2=n∑(xi−x)2
⇒σ2=6(a−55)2+(b−55)2+132+112+72+52=194
⇒(a−55)2+(b−55)2+364=1164
⇒(110−b−55)2+(b−55)2=800
⇒2(55−b)2=800
⇒(55−b)=20
⇒b=35
⇒a=75
⇒a+3b=75+105=180
Let the mean and the variance of 6 observation a,b,68,44,48,60 be 55 and 194, respectively if a>b, then a+3b is
Held on 31 Jan 2024 · Verified 6 Jul 2026.
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