Statistics Test...

The numbers in set P denote the distance of certain positive integers from -1 on the number line. The numbers in set Q denote
the distance of the same integers from 1 on the number line. Which of the following statements is true about the standard deviation of the sets P and Q?

List A: 20, 4, 8, x
List B: 8, 3, 6, 12, -4
List A above has 4 numbers and List B above has 5 numbers. What is the value of x?

(1) The range of the numbers in List A is equal to the range of the numbers in List B

(2) The median of the numbers in List A is equal to the median of the numbers in List B.

When positive integer y is added to each of the first n non-negative integers, which of the following statements is true?
I. If the median of the resulting numbers is  then n is odd

II. The arithmetic mean of the resulting numbers is equal to the median of the resulting numbers
III. The arithmetic mean of the resulting numbers is y units greater than the arithmetic mean of the first n positive integers.

If a, b and c are positive integers, what is the average (arithmetic mean) of a and c?
1. The average of a + b and 4 is 6
2. The average of a + c and b is 18

In an inter-state Mathematics Olympiad, the distribution of the scores obtained by the participating students is symmetric about
the mean m. 68 percent of the distribution lies within one standard deviation d of the mean and 95 percent of the distribution lies
within 2 standard deviations of the mean. If there were 70 students who scored more than Ricky, 428 students who scored less than Ricky and none that scored equal to him, his score must lie between

The average (arithmetic mean) of the prime numbers that lie between 10 and 20 is how much greater than the average of the
prime numbers that lie between 1 and 10?

A group of students was participating in a quizzing competition consisting of 3 rounds. A student had to clear the first round to move into the second round and so on till he cleared all the rounds. What was the median number of the rounds cleared by the students in the quiz?
(1) 20 percent of the students could not clear round 1 of the quiz
(2) 40 percent of the students could clear round 2 but could not clear round 3.

Arrange the following sets in the order of the increasing magnitude of their mean to standard deviation ratio.
I. {50, 60, 70, 80}
II. {35, 40, 45, 50}
III. {90, 110, 130, 150}

Set P has n integers. What is the standard deviation of Set P?
(1) The range of Set P is equal to zero
(2) The mean of Set P is equal to the median of Set P

In triangle ABC (not shown), is the range of the angles of the triangle greater than 90^o ?
(1) The median angle of triangle ABC is 70^o
(2) The difference between the two larger angles of triangle ABC is 10^o