Question 5 Find the mean and variance for the data
xi 92 93 97 98 102 104 109
f i 3 2 3 2 6 3 3
Class X1 - Maths -Statistics Page 371
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see the daigram ,
we get ,
∑fᵢ = 22 ,
∑fᵢxᵢ = 2200
∑fᵢxᵢ² = 220640
now,
Mean = ∑fᵢxᵢ/∑fᵢ
= 2200/22
= 100
now, variance = ∑fᵢxᵢ²/∑fᵢ - (mean)²
= 220640/22 - (100)²
= 10029.09 -10000
= 29.09
we get ,
∑fᵢ = 22 ,
∑fᵢxᵢ = 2200
∑fᵢxᵢ² = 220640
now,
Mean = ∑fᵢxᵢ/∑fᵢ
= 2200/22
= 100
now, variance = ∑fᵢxᵢ²/∑fᵢ - (mean)²
= 220640/22 - (100)²
= 10029.09 -10000
= 29.09
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