Correct Answer: C

Rationale: The correct answer is C: 'As elevation increases, temperature decreases.' In a negative correlation, the variables move in opposite directions. As elevation rises, temperature tends to decrease. Choice A is incorrect because a negative correlation implies that as one variable increases, the other decreases. Choices B and D are incorrect because they suggest that temperature either remains the same or increases as elevation decreases or increases, which is inconsistent with a negative correlation.

Correct Answer: C

Rationale: To find the combined work rate, you add the individual work rates: 1/2 + 1/3 = 5/6. This means that together, they can mow 5/6 of the lawn per hour. To determine how long it would take for both A and B to mow the entire lawn, you take the reciprocal of 5/6, which gives you 6/5 or 1.2 hours. Therefore, it would take 1.2 hours for person A and person B to mow the lawn together. Choice A (5 hours) is incorrect because it does not consider the combined efficiency of both workers. Choice B (2.5 hours) is incorrect as it does not reflect the correct calculation based on the combined work rates of the two individuals. Choice D (1 hour) is incorrect as it doesn't consider the fact that the combined rate is less than the individual rate of person A alone, thus taking longer than 1 hour.

Correct Answer: B

Rationale: To determine the greatest value among the choices, you need to convert all options to a common format. In this case, converting fractions to decimals will help compare them. When 7 · 5 is calculated, it equals 1.4, which is greater than 0.729 (choice C) and 0.78 (choice A when rounded). The percentage 73% (choice D) is equivalent to 0.73, making 7 · 5 the largest value. Therefore, the correct answer is B. Choice A is smaller than B, as 43 · 55 equals approximately 0.78. Choice C is smaller than B, as 0.729 is less than 1.4. Choice D is smaller than B, as 73% is equal to 0.73, which is less than 1.4.

Correct Answer: A

Rationale: To find the least common denominator for fractions 1/2, 2/3, and 4/5, we need to identify the least common multiple of the denominators. The denominators are 2, 3, and 5. The least common multiple of 2, 3, and 5 is 30. Therefore, 30 is the least common denominator for these fractions. Choice B (25), C (7), and D (19) are incorrect because they are not the least common multiple of the denominators of the given fractions.

Correct Answer: B

Rationale: To find the ratio of girls to boys, divide the number of girls by the number of boys: 26/22 = 13/11. Therefore, the correct ratio is 13:11. Choice A is incorrect as it includes an extra '00'. Choice C is incorrect as it reverses the order of girls to boys. Choice D is incorrect as it reverses the order and provides the ratio of boys to girls.