Let the other two numbers be x and y. ∴ Mean =‌
−1+1+2+x+y
5
⇒‌‌0=‌
2+x+y
5
⇒‌‌x+y=−2.....(i) and variance =‌
Σ(xi−x)2
n
⇒‌‌2=‌
[(−1−0)2+(1−0)2+(2−0)2+(x−0)2+(y−0)2]
5
⇒‌‌10=1+1+4+x2+y2 ⇒‌‌x2+y2=4......(ii) On squaring Eq. (i), we get x2+y2+2xy=4 ⇒‌‌4+2xy=4  [From Eq. (ii)] ⇒‌‌xy=0 Now, x−y=√(x+y)2−4xy =√(−2)2−4×0=2  [From Eq. (i)] ⇒‌‌x−y=2.....(iii) On solving Eqs. (i) and (iii), we get 2x=0⇒x=0 and y=−2