Statistics
Mean & Standard Deviation
MMTS_Full_Test_20
Grade 12
Question:
The mean and standard deviation of the marks of 200 candidates were found to be 40 and 15 respectively. Later, it was discovered that one student's marks 40 was wrongly read as 50. The correct mean and standard deviation, respectively are
14.98, 39.95
39.95, 14.98
39.95, 224.5
39.00, 14.00
Step-by-Step Solution
Key Concept: Correct sum and sum of squares; recalculate mean and variance
New mean $=\frac{200\cdot 40-50+40}{200}=39.95$. New variance: recalculate to get SD $\approx 14.98$.
Correct Answer: 2