Try the following GMAT Problem Solving question on how the average(arithmetic mean) of a data set changes when a data value is replaced by another number.

Question 54:

The average (arithmetic mean) of a list of $n$ numbers is $m$. If one of the numbers with a value of $6$ is replaced by another number of value $12$, then what is the new average for the list of $n$ numbers ?

1. $\quad \dfrac{m-6}{n}$

2. $\quad \dfrac{m+6}{n}$

3. $\quad \dfrac{m}{n}-6$

4. $\quad m-\dfrac{6}{n}$

5. $\quad m+\dfrac{6}{n}$

 
Try the following GMAT data sufficiency question on algebra involving equations and inequalities with two variables.

Question 53:

Is $ab=0$ ?

1. (1) $b < |b|$
2. (2) $ab = 2a$

1. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
2. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
3. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
4. EACH statement ALONE is sufficient.
5. Statements (1) and (2) TOGETHER are NOT sufficient.

 
Try the following GMAT Problem Solving question on finding prime factors of a summation.

Question 52:

If $S$ is the sum of the first fifty positive integers, then what is the sum of all the distinct prime factors of $S$ ?

1. $\quad 20$

2. $\quad 25$

3. $\quad 32$

4. $\quad 41$

5. $\quad 56$

 
Try the following GMAT Problem Solving question on conditions under which algebraic expressions are undefined.

Question 51:

For what real values of $x$ is the expression $\dfrac{3(x+3)}{(x-1)(x+2)}$ not defined ?

1. $\quad x=-3 \; \textrm{only}$

2. $\quad x=-2 \; \textrm{only}$

3. $\quad x=1 \; \textrm{only}$

4. $\quad x=-2 \; \textrm{or} \; 1 \; \textrm{only}$

5. $\quad x=-3, -2, \textrm{or} \; 1 $

 
Try the following GMAT Problem Solving question on plane geometry and finding area of a rectangular picture frame.

Question 50:

The figure below shows a picture frame that consists of a rectangular photograph(white region) surrounded by a border of uniform width of $x$ inches. The perimeter of the photograph is $27$ inches, and the area of the border(grey region) is $70$ square inches. What is the perimeter in inches of the entire picture frame including the border?

1. $\quad 37$

2. $\quad 43$

3. $\quad 48$

4. $\quad 51$

5. $\quad 56$