Hi David,

Can you please explain how you arrived at the answer of 75%

Thanks,
Philip

Hi Philip,

The answer was truncated from the quiz, which i just fixed, so it reads now:

“We don’t need the distribution given a mean and finite variance, this is the cleverness of Chebyshev’s inequality. P[ABS(X-mean) <= (constant)(standard deviation) >1 - 1/c^2. In this case, we want the probability variable will fall within two standard deviations: P >=1- 1/2^2 = 1-1/4 = 75%. The probability is at least 75%. Or put another way, probability return is outside the 2 standard deviation interval is LESS THAN OR EQUAL TO 25%.”

David