Answer :
Answer B.
∑fx=1637,∑fx
2
=127663,∑f=21
x
ˉ
=Mean=
∑t
∑fx
=77.95
σ
2
=
∑f
∑fx
2
−(
x
ˉ
)
2
=
21
127663
−(77.95)
2
=2.987
σ=1.728
∑fx=1637,∑fx
2
=127663,∑f=21
x
ˉ
=Mean=
∑t
∑fx
=77.95
σ
2
=
∑f
∑fx
2
−(
x
ˉ
)
2
=
21
127663
−(77.95)
2
=2.987
σ=1.728