设成绩分别为:x 1,x 2,…x n,
.
x =
1
n (x 1+x 2+x 3…+x n)=75,
方差S 2=
1
n [(x 1-
.
x ) 2+(x 2-
.
x ) 2+…+(x n-
.
x ) 2]=40,
换算后成绩分别为1.2x 1,1.2x 2,…1.2x n,
.
x =
1
n (1.2x 1+1.2x 2+1.2x 3…+1.2x n)=1.2×
1
n (x 1+x 2+x 3…+x n)=1.2×75=90,
方差S 2 2=
1
n [(1.2x 1-1.2
.
x ) 2+(1.2x 2-1.2
.
x ) 2+…+(1.2x n-1.2
.
x ) 2]=1.2 2×
1
n [(x 1-
.
x ) 2+(x 2-
.
x ) 2+…+(x n-
.
x ) 2]=1.44×40=57.6,
故答案为:90,57.6.