Let 1st5 students are
x1,x2,x3,x4 and x5
∴18=E(x2)−(E(x))2
=5x12+x22+x32+x42+x52−(150)2
⇒x12+x22+x32+x42+x52=112590
∴ new variance =6x12+x22+....+x52+1562−(151)2 [Sincenewmean=6150×5+156=151]
=6112590+24336−22801
=20
5 students of a class have an average height 150cm and variance 18cm2. A new student, whose height is 156cm, joined them. The variance (incm2) of the height of these six students is:
Held on 9 Jan 2019 · Verified 6 Jul 2026.
22
16
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20
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