the mean and standard deviation of 100 observations were calculated as 40 and 5.1 resp. by a student who took by mistake 50 instead of 40 for one observation. what are correct mean and standard deviation?
Answers
Answered by
8
Mean=Sum of all observations/Number of obervations
Before realizing mistake
40=Sum of all observations/100
Sum of all observations=400
After realizing mistake
Replace 40 by 50. But How? We cannot replace them until we have all observations but we have sum of observations which will get effected by replacing 40 by 50. So new sum will be 10 less
Sum of all observations=390
New mean=390/100=39
Use formula for SD where they used sum, sum of squares.
Answered by
15
Answer:
Correct SD = 5
Step-by-step explanation:
Formula Explanation
• Correct Mean = Summation X (Wrong) - Incorrect Value + Correct Value
/ No. of Observations
Attachments:
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