Statistics Test...

Find the mean for the following data using step deviation method.

A random variable $$X$$ has the probability distribution given below. Its variance is 

Brian got grades of $$92,89$$ and $$86$$ on his first three math tests. What grade must he get on his final test to have an overall average of $$90$$?

The mean of a finite set X of numbers is $$14$$, the median of this set of numbers is $$12$$, and the standard deviation is $$1.8$$. A new set Y is formed by multiplying each member of the set S by $$3$$. Determine the correct statements w.r.t. set Y:
I. The mean of the numbers is set Y is $$42$$
II. The median of the numbers in set Y is $$36$$
III. The standard deviation of the numbers is set Y is $$5.4$$

Grades for the test on proofs did not go as well as the teacher had hoped. The mean grade was 68, the median grade was 64, and the standard deviation was 12. The teacher curves the score by raising each score by a total of 7 points. Which of the following statements is true?
I. The new mean is 75.
II. The new median is 71.
III. The new standard deviation is 7.

The mean of $$48, 27, 36, 24, x$$, and $$2x$$ is $$37.x =$$

The average of six numbers is 4. If the average of two of those numbers is 2, what is the average of the other four numbers?

Find the arithmetic mean of $$\dfrac {1}{2}, \dfrac {1}{3}, 2n$$ and $$m$$.

Find the coefficient of variation.

Which of the following can be used as measures of dispersions?