If x * y represents the number of integers greater than x and less than y, what is the value of –π * 2? (π is pie)

If $A,B,C$ and $D$ are positive integers such that $4A=9B,17C=11D$, and $5C=12 A$, then the arrangement of the four numbers from greatest to least is

If the average (arithmetic mean) of five distinct positive integers is 10, what is the least possible value of the greatest of the five integers?

The table above shows the age of 6 friends. The average age of the six friends is 16 years. If no person is less than 14 or greater than 20 years of age, what is the maximum average age of the 4 eldest people in the group?

The average age of a couple, a day before the birth of their first child, was 26 years. Exactly 6 years after the birth of their first child, they had their second child, what was the approximate average age of the family of four, 6 years after the birth of the second child? (in years)

The figure above shows the standard normal distribution with mean 0 and standard deviation 1, including approximate percent of the distribution corresponding to the six regions shown above. The random variable x is normally distributed with standard deviation of 10 and value x = 135 is at the 20th percentile of the distribution. Of the following which is the best estimate of the mean of the distribution?

List I = 5, 10, 15, 20, 25

List II = 15, 15, 40, –30, 20, X

What is the value of X, if mean of List I is same as mean of List II?

If average of (a+b)² and (a–b)² is 70, then what is the value of a²+b²?

A cookery course is divided into two groups. In group X, the average score in the test was 76. In group Y, the average score in the test was 70. If the average score of all 30 trainees in the course was 74, how many trainees are in group X?

The average (arithmetic mean) score of a class was 70. If the boys’ average was 65 and that of girls’ was 80, what could be the number of boys and girls, respectively, in the class?