Answer: 50.9.
- A 50.9
- B 49.1
- C 59
- D 50.09
Correct answer: A. 50.9
Explanation: Corrected total increases by 90, so the mean rises by 90/100 = 0.9 to 50.9.
In a perfectly normal (bell-shaped) distribution, mean, median, and mode all coincide at the centre; about 68% of data falls within 1 standard deviation of the mean, 95% within 2, and 99.7% within 3 - the empirical rule used to judge how typical or extreme a value is.
Concept context
Mean, median, mode, standard deviation, and data interpretation