1.

For the frequency distribution

Answer»


SOLUTION :`because` Sum of FREQUENCIES
`x-2+x+x^(2)+(x+1)^(2)+2X+x+1=60`
`rArr "" 2x-2+x^(2)+x^(2)+1+2x+2x+x+1=60`
`rArr ""2x^(2)+7x=60`
`rArr2x^(2)+7x-60=0`
`rArr2x^(2)+7x-60=0`
`2x^(2)+15x-8x-60=0`
`rArr "" x(2x+15)-4(2x+15)=0`
`rArr ""(2x+15)(x-4)=0`
`x=-(15)/(2),4`
`rArr""x=(-15)/(2)`

Mean `=A+(Sigma f_(i)d_(i))/(Sigmaf_(i))=3+((-12)/60)=2.8`
`sigma=sqrt((Sigmaf_(i)d_(i)^(2))/(Sigma_(f_(i)))-((Sigmaf_(i)d_(i))/(Sigmaf_(i)))^(2))=sqrt(78/60-((-12)/60))^(2)`
`sqrt(1.3-0.04)=sqrt(1.26)=112`


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