Question 1

The price of gold was $1061 per ounce on December 31 and has risen 14.78 percent since that time. What is the price per ounce now?

Accepted Answer

To find the new price, calculate the increase by multiplying the original price by the percentage increase: $1061 * 14.78% = $156.82. Add this to the original price: $1061 + $156.82 = $1217.82, which rounds to $1218.

Question 2

Following are data on the populations and numbers of death row prisoners for several states.

Which state has the highest number of death row prisoners relative to the size of its population?

Accepted Answer

D

Question 3

Michelle's income two years ago was $220,000. Last year, her income was $300,000. The percent change in Michelle's income was:

Accepted Answer

To find percent change between two values, we use the formula:

percent change = (new value - old value) / old value x 100%

Using this formula for Michelle's income, we get:

percent change = (300,000 - 220,000) / 220,000 x 100%
percent change = 80,000 / 220,000 x 100%
percent change = 0.3636 x 100%
percent change = 36.36%

Rounding to one decimal place, we get a percent increase of 36.4%. Therefore, choice A) is the correct answer.

Question 4

A web page headline said, "Winter Storm Jonas Slams the East Coast-Airline Cancels All But 0.1 Percent, or 62, Out of the Scheduled 6000 Flights." The correct percentage canceled was:

Accepted Answer

If 62 flights out of 6,000 were canceled, that is approximately 1 percent. To confirm this, we can divide 62 by 6,000 and multiply by 100 to get 1.03 percent. Therefore, the correct answer is nearly 1 percent (B).

Question 5

The net asset value of a mutual fund has decreased from $2,700 on December 31 to $1,330 now. The percent decrease in value is about:

Accepted Answer

To find the percent decrease, we need to calculate the difference between the starting and ending values, then divide that difference by the starting value, and finally multiply by 100.

Starting value = $2,700
Ending value = $1,330

Difference = $2,700 - $1,330 = $1,370

Percent decrease = (Difference / Starting value) x 100
= ($1,370 / $2,700) x 100
= 0.507 x 100
= 50.7%

Therefore, the answer is D) 50.7 percent.

Question 6

Which of the following statements do you think could possibly be true?

Accepted Answer

The answer of Which of the following statements do you...

Question 7

An ad for a new mouth rinse says that it "reduces plaque on teeth by 200%." What does this mean?

Accepted Answer

It's nonsense because removing 100% of the plaque already removes all of it, and you cannot remove more than there was at the beginning.

Question 8

An ad for a new heartburn treatment says that it "reduces heartburn by 300%." What does this mean?

Accepted Answer

Reducing something by 100% means eliminating it entirely, so claiming a reduction of 300% is mathematically nonsensical.

Question 9

Before starting a body building program, Joe weighed 185 pounds. At the end of the program, he weighed 202 pounds. This is a percentage gain of:

Accepted Answer

The percentage gain is calculated by the formula: [(Final weight - Initial weight) / Initial weight] * 100. So, [(202 - 185) / 185] * 100 = 9.19 percent.

Question 10

The Dow Jones Industrial Average (DJIA) is the most common measure of stock market prices. Suppose that the DJIA starts at 17,149 points and drops 500 points. This is a decrease of:

Accepted Answer

To calculate the percent decrease, we need to divide the amount of decrease by the original value, then multiply by 100.

Percent decrease = (Amount of decrease / Original value) x 100 
Percent decrease = (500 / 17,149) x 100 
Percent decrease = 2.92 or 2.9% (rounded to one decimal place)

Therefore, the answer is B.

Question 11

The average wage of production workers (adjusted for the effects of inflation) was $11.08 an hour in 1981 and $10.35 an hour in 1991. In the decade of the 1980s, wages went down by about

Accepted Answer

The percentage decrease in wages is calculated as ((11.08 - 10.35) / 11.08) * 100%, which equals approximately 6.6%.

Question 12

In the last half of 2015, the price of Apple, Inc. (AAPL) common stock dropped from $126.60 per share to $105.26 per share. What percent decrease is this?

Accepted Answer

The percent decrease is calculated as follows:Percent decrease = (Original price - New price) / Original price * 100Percent decrease = ($126.60 - $105.26) / $126.60 * 100Percent decrease = $21.34 / $126.60 * 100Percent decrease = 0.1686 * 100Percent decrease = 16.86%

Question 13

A 500-point drop in the DJIA was a big drop when the DJIA was at 2246 in October of 1987 and a much smaller drop when the DJIA reached 11,421 in September of 2008. The percent by which stock prices fall is a more meaningful measure. The lesson here is that

Accepted Answer

This is because rates or percentages take into account the size or scale of the variable being measured, making it a more standardized measure that is comparable across different time periods, populations, or groups. Counts or raw numbers can be misleading if the size or scale of the variable changes over time or across groups.

Question 14

A student reports that, of a simple random sample of 25 college undergraduate students, 18% were working at least two jobs. We know that the student has made a mistake (or maybe really did not conduct the survey). Why?

Accepted Answer

Given a sample of 25 students, the smallest change in count (1 student) corresponds to a 4% change in percentage (since 1/25 = 0.04 or 4%). Also, 18% of 25 is 4.5, which is not possible since you cannot have half a student. Therefore, both B and C are correct reasons.

Question 15

A student reports that, of a simple random sample of 50 college undergraduate students, 21% were taking more than fifteen credit hours. We know that the student has made a mistake (or maybe really did not conduct the survey). Why?

Accepted Answer

Given a sample of 50 students, the percentage of any subgroup should indeed be a multiple of 2% because 1 student represents 2% of the sample (1/50 = 0.02 or 2%). Additionally, 21% of 50 students equals 10.5, which is not possible since you cannot have a fraction of a student in a real-world sample. Therefore, both A and C are correct, making D the correct choice.

Question 16

In 1989, 2.0 billion cigars were smoked in the United States. In 2015, 2.4 billion cigars were smoked. What percentage change is this?

Accepted Answer

To find the percentage change, we use the formula:

((New Value - Old Value) / Old Value) x 100

Using this formula, we get:

((2.4 billion - 2.0 billion) / 2.0 billion) x 100 = 0.2 x 100 = 20%

Therefore, the percentage change is a 20% increase, which corresponds to choice D.

Question 17

According to the FBI Uniform Crime Report, the robbery rate in the United States is 202 per 100,000 people. At that rate, how many robberies would there be in a state the size of Indiana (5.8 million people)?

Accepted Answer

To find the number of robberies in a state the size of Indiana, we can use the following calculation:
Number of robberies = (Robbery rate per 100,000 people) x (Population of the state / 100,000)
Number of robberies = 202 x (5,800,000 / 100,000)
Number of robberies = 202 x 58
Number of robberies = 11,716 
Therefore, the answer is B, about 12,000.

Question 18

A student reports that, of a simple random sample of 200 college undergraduates, 37% were female and 41% were male. We know that the student has made a mistake because

Accepted Answer

The student's mistake is that the percentages of males and females add up to more than 100%, which is not possible in a simple random sample.

Question 19

Dr. Stat's library of literary classics includes issues of certain scholarly periodicals. The total number of issues of four such periodicals, together with the percentages of Dr. Stat's entire library that they comprise, are as follows:

Exactly one of the percentages in this table is incorrect. Which is it?

Accepted Answer

The answer of Dr. Stat's library of literary classics includes...

Question 20

A student reports that, of a simple random sample of 100 college undergraduates, 54% were female and 49% were male. We know that the student has made a mistake because

Accepted Answer

The percentages of females and males add up to more than 100%, which is not possible in a simple random sample.

Quiz 9: Do the Numbers Make Sense