What is the probability for:10 members of the 50-member sample were grade E males. The probability of being a male in grade E is 10/50 or 1/5. There is a 20% chance that a grade E male will be selected at random.
10 members of the 25-member part of the sample that were male were also in grade E. Given that a male was selected; the probability of that male being in grade E is 10/25 or 2/5. There is a 40% chance that grade E will be randomly selected out of the males in the sample.
The probabilities are different because the 40% probability assumes that a male has already been chosen. This means that the whole group only contains 25 members. The 20% probability includes a larger number of possible outcomes because it includes females, but the number of favorable outcomes did not increase.
Consider each group (Male and Female separately) and assume the salaries follow a Normal Probability distribution:
The third quartile of the male data is 64.3 thousand dollars. This represents the 75th percentile because 75% of the data fall below this amount. Those who make between 64.3k and 78.7k fall within the 75th percentile.
The third quartile of the female data is 57 thousand dollars. This represents the 75th percentile because 75% of the data fall below this amount. Those who make between 57k and 75.6k fall within the 75th percentile.
14 out of the 25 males in the sample make more than 50k, so the probability that a randomly selected male will make more than 50k is 14/25 or 56%.
4 out of the 25 females in the sample make between 30k and 40k, so the probability that a randomly selected female will make between 30k and 40k is 4/25 or 16%.