The frequencies of the scores 30,50,60 and 40 are respectively equal to x, x+2, x-8. and x+6. If the mean of these scores is 40, What is the frequency of the score 40 ?
Answers
Answered by
0
Answer:
With the given distribution , xi=35,45,55,65,75,85,95
fi=3,7,12,15,8,3,2
∴xifi=105,315,660,975,600,255,190
∴∑fi=50
∑xifi=3100
∴Mean(X¯¯¯)=∑xifi∑fi=310050=62
Now, |xi−x¯|=27,17,7,3,13,23,33
|xi−x¯|2=729,289,49,9,169,529,1089
∴|xi−x¯|2fi=2187,2023,588,135,1352,1587,2178
∴ Variance, (σ)2=∑|xi−x¯|2fi∑fi=1005050=201
Standard deviation, (σ)=201−−−√≅14.177.
Similar questions