The question asks for the average amount of money raised per student. The number of cookies sold is extra information. First, sum the money raised by each student: $24 + $30 + $22 + $24 = $100. Then, divide by the number of students, which is 4. $100 ÷ 4 = $25. The average amount raised was $25.00 per student.

The question asks for the average number of points, so the jersey numbers (#5, #10, #23, #32) are irrelevant. To find the average, add the points scored: 12 + 18 + 6 + 16 = 52. Then, divide by the number of players, which is 4. 52 ÷ 4 = 13. The average was 13 points per player.

To find Maria's average, sum the number of pages she read and divide by the number of days. Maria's total pages: 20 + 15 + 25 + 18 + 22 = 100 pages. She read for 5 days. Her average is 100 ÷ 5 = 20 pages per day. The information about her brother Leo is not needed.

The question asks for the average number of pets, so the number of children is not needed. Sum the number of pets: 2 + 3 + 1 + 2 = 8 pets. There are 4 families. Divide the total number of pets by the number of families: 8 ÷ 4 = 2. The average is 2 pets per family.

When you encounter average problems, you need to identify what's being averaged and what information is relevant. This question asks for the average number of cars per hour, so focus only on the car data.

To find an average, you add up all the values and divide by the number of time periods. Here, you have three one-hour periods with car counts of 150, 200, and 160. The total number of cars is $$150 + 200 + 160 = 510$$ cars. Since this happened over 3 hours, the average is $$510 ÷ 3 = 170$$ cars per hour.

Looking at the wrong answers: Choice A (160 cars) might tempt you if you accidentally used only the third hour's data or tried to find some other pattern in the numbers. Choice B (180 cars) could result from a calculation error, perhaps mixing up the addition or division steps. Choice D (510 cars) is the total number of cars, not the average—this is a common trap where students stop after finding the sum and forget to divide by the number of time periods.

Notice that the 50 pedestrians are completely irrelevant to this problem since you're only asked about cars per hour. This is a red herring designed to test whether you can identify what information matters.

Strategy tip: In average problems, always double-check that you're dividing the correct total by the correct number of items or time periods. Write out "total ÷ count" to avoid the common mistake of reporting the sum instead of the average.

When you encounter questions about averages, remember that the average (or mean) is the total of all values divided by the number of values you're averaging.

To find the average number of students who chose each sport, you need to add up all the students who chose these three sports, then divide by 3 (since there are three sports).

Let's calculate: 12 students chose soccer + 10 chose basketball + 8 chose baseball = 30 total students. Now divide by the number of sports: $$30 ÷ 3 = 10$$ students per sport on average.

Looking at the wrong answers: Choice A (8 students) is simply the number who chose baseball - this represents just one sport, not the average across all three. Choice B (12 students) is the number who chose soccer, again just one individual sport rather than the average. Choice D (30 students) is the total number of students surveyed, but the question asks for the average per sport, not the total.

The trap here is confusing individual values with the calculated average, or mixing up the total with the average.

Study tip: For average problems, always identify what you're averaging (in this case, the number of students per sport), add up all the relevant values, and divide by how many items you're averaging. Don't be tempted to pick numbers that appear in the problem - the average is usually a calculated result, not a given value.

The question asks for the average number of fish per tank. The volume of water in each tank is extra information. Sum the number of fish in each tank: 10 + 15 + 11 = 36 fish. There are 3 tanks. Divide the total number of fish by the number of tanks: 36 ÷ 3 = 12. The average is 12 fish per tank.

When you encounter an average problem, you need to add up all the values and divide by the number of items. This question gives you extra information about the trees' ages, but since it only asks for average height, you can ignore that data completely.

To find the average height, add up all four tree heights: 30 + 40 + 35 + 35 = 140 feet. Then divide by the number of trees: $$140 ÷ 4 = 35$$ feet.

Let's examine why the other answers are incorrect. Choice A (17.5 feet) represents the average age of the trees, not their height. If you accidentally used the age data (15 + 20 + 18 + 17 = 70, then 70 ÷ 4 = 17.5), you'd get this wrong answer. Choice B (70 feet) is the sum of all the ages without dividing by 4 - this shows you found a total but forgot the final division step. Choice C (37.5 feet) might result from a calculation error, perhaps averaging only some of the heights or making an arithmetic mistake when adding or dividing.

The correct answer is D (35 feet).

Study tip: In average problems, identify exactly what quantity you're being asked to average, then ignore any irrelevant data. Always remember that average equals sum divided by count. Also, do a quick reasonableness check - your average should fall somewhere between the highest and lowest values in your data set.

When you see a question asking for an "average," you need to find the mean by adding all the values together and dividing by the number of items. Notice that this question gives you information about both call lengths and costs, but only asks about the average length - so you can ignore the cost information entirely.

To find the average length of the four calls, add up all the call times: 12 + 18 + 10 + 20 = 60 minutes total. Then divide by the number of calls: $$\frac{60}{4} = 15$$ minutes per call on average.

Let's examine why each wrong answer choice appears: Choice (A) 12 minutes is simply the length of the first call listed - this is a trap for students who might think the first value given is somehow special. Choice (B) 60 minutes is the total time of all calls combined, which you'd get if you forgot to divide by the number of calls. Choice (C) 16 minutes might result from a calculation error, perhaps incorrectly adding the call lengths or dividing incorrectly.

The correct answer is (D) 15 minutes.

Remember this key strategy for average problems: always identify exactly what you're averaging (here, call lengths, not costs), add up only those relevant values, and divide by the count. Questions often include extra information to distract you - stay focused on what's actually being asked.

This problem tests your understanding of finding the average (also called the mean) of a set of numbers. When you see a question asking for an average, remember that you need to add up all the values and divide by how many values you have.

To find the average running time, you need to add all four times together and divide by 4 (since there are 4 runners). The times are 12, 14, 11, and 13 seconds. Adding these: $$12 + 14 + 11 + 13 = 50$$ seconds total. Now divide by the number of runners: $$50 ÷ 4 = 12.5$$ seconds. This confirms that D) 12.5 seconds is correct.

Let's examine why the other answers are wrong. Choice A) 3.5 seconds represents a common calculation error where students might subtract instead of add, or divide incorrectly. Choice B) 50 seconds is the total sum of all times, but this is before dividing by 4 to get the average - a frequent mistake where students stop halfway through the calculation. Choice C) 14 seconds is simply one of the individual running times, showing confusion between finding an average versus identifying a single value from the data set.

The key information about lane numbers (2, 3, 4, and 5) is irrelevant to solving this problem - it's included to test whether you can identify what information is actually needed. On quantitative reasoning questions, always focus on the numbers that directly relate to what's being asked, and remember that average equals sum divided by count.