which of the following is not a way to write 40 percent of n

ATI TEAS 7

TEAS Math Practice Test

1. Which of the following is NOT a way to write 40 percent of N?

A. 0.4N
B. N/40
C. 2/5 N
D. 40N/100

Correct answer: B

Rationale: The correct answer is B: N/40. To find 40% of N, you multiply N by 0.4, so 0.4N is the correct representation. Choice B, N/40, is incorrect because dividing N by 40 does not give you 40% of N. Choice C, 2/5 N, is equivalent to 40% of N since 2/5 is the same as 40% when simplified. Choice D, 40N/100, is also correct since 40% can be represented as 40/100, which simplifies to 0.4, making 40N/100 another valid way to write 40% of N.

2. Mom's car drove 72 miles in 90 minutes. How fast did she drive in feet per second?

A. 0.8 feet per second
B. 48.9 feet per second
C. 0.009 feet per second
D. 70.4 feet per second

Correct answer: B

Rationale: To convert miles per hour to feet per second, you need to convert miles to feet and minutes to seconds. First, convert 72 miles to feet using the conversion factor 1 mile = 5280 feet: 72 miles * 5280 feet/mile = 380160 feet. Then, convert 90 minutes to seconds: 90 minutes * 60 seconds/minute = 5400 seconds. Now, to find the speed in feet per second, divide the distance traveled in feet by the time in seconds: 380160 feet / 5400 seconds = 70.4 feet per second. Therefore, the correct answer is 70.4 feet per second. Choice A, 0.8 feet per second, is incorrect as it is a much lower speed. Choice C, 0.009 feet per second, is also incorrect as it is too low. Choice D, 70.4 feet per second, would be correct if the conversion calculations were accurate, but in this case, it's not the correct answer.

3. You measure the width of your door to be 36 inches. The true width of the door is 75 inches. What is the relative error in your measurement?

A. 0.52%
B. 0.01%
C. 0.99%
D. 0.10%

Correct answer: A

Rationale: The relative error is calculated using the formula: (|Measured Value - True Value| / True Value) * 100%. Substituting the values given, we have (|36 - 75| / 75) * 100% = (39 / 75) * 100% ≈ 0.52 * 100% = 0.52%. Therefore, the relative error in measurement is approximately 0.52%. Choice A is correct because it reflects this calculation. Choice B is incorrect as it represents a lower relative error than the actual value obtained. Choice C is incorrect as it overestimates the relative error. Choice D is incorrect as it underestimates the relative error.

4. What is the sum of 3/8 and 5/8?

A. 1
B. 1 1/4
C. 01-Feb
D. 03-Apr

Correct answer: A

Rationale: To find the sum of fractions, add the numerators if the denominators are the same. Here, 3/8 + 5/8 = (3+5)/8 = 8/8 = 1. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not represent the correct sum of the fractions provided in the question.

5. A lab technician took 100 hairs from a patient to conduct several tests. The technician used 1/7 of the hairs for a drug test. How many hairs were used for the drug test? (Round your answer to the nearest hundredth.)

A. 14
B. 14.2
C. 14.29
D. 14.3

Correct answer: C

Rationale: To find how many hairs were used for the drug test, you need to calculate 1/7 of 100. 1/7 of 100 is 14.2857, which rounds to 14.29 when rounded to the nearest hundredth. Therefore, 14.29 hairs were used for the drug test. Choice A is incorrect as it does not account for rounding to the nearest hundredth. Choices B and D are incorrect as they do not accurately reflect the calculated value after rounding.