Practice Test 6 - GMAT Quantitative

20 questions. Answer them in any order, then submit to see your score and every explanation.

If a positive integer $n$ is divisible by both $45$ and $70$ , what is the least possible value of $n-105$ ?
A researcher studying test scores finds that Class A has a standard deviation of 12 points and Class B has a standard deviation of 8 points. Both classes have the same mean score. The researcher then removes the top 10% and bottom 10% of scores from each class. Which statement about the new standard deviations is most likely true?
A jar contains red and blue marbles in the ratio 3 to 4. After 10 red marbles are added and 4 blue marbles are removed, the ratio becomes 5 to 6. How many blue marbles were in the jar originally?
Let $k=\dfrac{(x+1)^{2}-(x-1)^{2}}{x}$ for all nonzero $x$ . What is the value of $k$ ?
If $\sqrt{x + \sqrt{x + \sqrt{x + \ldots}}} = 5$ for $x > 0$ , what is the value of $x$ ?
A manufacturing process has a 15% defect rate. If 8 items are randomly selected for inspection, what is the probability that exactly 2 items are defective?
The price of a stock increases by $x$ % on Monday and decreases by $y$ % on Tuesday, resulting in a net decrease of 4% over the two days. If $x = 2y$ , what is the value of $y$ ?
Based on the bar graph, what percent of the students who took at least one of the two exams took exactly one of them?
Refer to the time-series plots. Over the 12 months shown, which company experienced the smaller standard deviation in monthly revenue?
If $\sqrt[4]{16x^8} = 2x^n$ for all positive values of $x$ , what is the value of $n$ ?
Which of the following intervals contains all real numbers $x$ satisfying $x^{2}-3x-4\le0$ ?
A coffee shop blends three types of beans: Colombian beans at $12 per pound, Brazilian beans at$ 8 per pound, and Ethiopian beans at $16 per pound. The shop creates a 50-pound blend using twice as many pounds of Colombian beans as Brazilian beans, and the remaining weight is Ethiopian beans. If the blend's average cost per pound is$ 12.80, how many pounds of Brazilian beans are used?
If the total cost for producing 50 widgets is $550 and the total cost for producing 80 widgets is $790, what is the fixed daily cost?
The height of a ball (in meters) tossed upward is given by $h(t)=-5t^{2}+20t+15$ , where $t$ is the time in seconds after the ball is thrown. After how many seconds does the ball reach its maximum height?
Let real number $s$ satisfy $|s+2|+|s-5|<10$ . Which of the following describes all possible values of $s$ ?
A survey of household incomes in City A reveals a standard deviation of $18,000, while the same survey in City B shows a standard deviation of $24,000. Both cities have the same median household income of $55,000. An economist concludes that City B has greater income inequality. Which statement best evaluates this conclusion?
A company calculates employee bonuses using a weighted average of three performance metrics: Quality (weight 40%), Efficiency (weight 35%), and Teamwork (weight 25%). If an employee's Quality score is 85, Efficiency score is 92, and the weighted average is 88, what is the Teamwork score?
In a survey of 180 professionals, 120 use laptops, 90 use tablets, and 60 use smartphones. Additionally, 50 use both laptops and tablets, 35 use both laptops and smartphones, and 25 use both tablets and smartphones. If 15 professionals use all three devices, how many professionals use exactly two of these three devices?
For positive real numbers $k$ and $n$ satisfying $2^{k}=10^{n}$ , which of the following expresses $n$ in terms of $k$ ?
If $\frac{x}{y} + \frac{y}{x} = 5$ and $xy \neq 0$ , then $\frac{x^2 + y^2}{xy}$ equals:

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