Try the following GMAT Quantitative Reasoning question on manipulating exponent expressions.

Question 65:

Suppose that $4^{x_1}=5$, $5^{x_2}=6$, $6^{x_3}=7$, $\ldots$ , $127^{x_{124}} = 128$. What is $x_1 x_2 \cdots x_{124}$ ?

1. $\quad 2$

2. $\quad \dfrac{5}{2}$

3. $\quad 3$

4. $\quad \dfrac{7}{2}$

5. $\quad 4$

 
Try the following GMAT Problem Solving question on statistics that requires being able to find the sum and average of a set of numbers when the values in the list are changed.

Question 64:

A set of $n$ numbers has the sum $s$. Each number of the set is increased by $20$, then multiplied by $5$, and then decreased by $20$. The sum of the numbers in the new set thus obtained is:

1. $\quad s+20n$

2. $\quad 5s+80n$

3. $\quad s$

4. $\quad 5s$

5. $\quad 5s+4n$

 
Try the following GMAT Problem Solving question on finding the maximum value of a quadratic algebraic expression.

Question 62:

For any real value of $x$ the maximum value of $8x-3x^2$ is:

1. $\quad 0$

2. $\quad \dfrac{8}{3}$

3. $\quad 4$

4. $\quad 5$

5. $\quad \dfrac{16}{3}$

 
Try the following GMAT Problem Solving question that tests your understanding of algebraic inequalities with three variables.

Question 58:

Which of the following must be true ?

1. If $xy < xz$, then $y < z$.
2. If $x^2y < x^2 z$, then $y < z$.
3. If $x-y < x-z$, then $z < y$.

1. $\quad \textrm{None}$
2. $\quad \textrm{I and II only}$
3. $\quad \textrm{II and III only}$
4. $\quad \textrm{I and III only}$
5. $\quad \textrm{I, II, and III}$