Correct Answer: A

Rationale: To add mixed numbers, first convert them to improper fractions. 6 3/4 = 27/4 and 8 1/6 = 49/6. Finding a common denominator, we get 27/4 + 49/6 = 81/12 + 98/12 = 179/12 = 14 & 11/12. Therefore, the correct answer is A. Choice B is incorrect as it does not simplify to the correct result. Choice C is in fraction form and not in mixed number form, making it incorrect. Choice D is not the correct sum of the given mixed numbers, so it is also incorrect.

Correct Answer: A

Rationale: To find the new width, we need to maintain the aspect ratio of the photo. The original height is 15 inches, which is equivalent to 1.25 feet. If the new height is 4 feet, the scaling factor for the height is 4/1.25 = 3.2. Therefore, to find the new width, we multiply the original width by this scaling factor: 1.25 feet * 3.2 ≈ 4 feet. So, the correct answer is approximately 2.1 feet (4 feet * (15 inches / 4 feet) ≈ 2.1 feet). Choices B, C, and D are incorrect as they do not consider the aspect ratio and calculate the new width incorrectly.

Correct Answer: B

Rationale: The value of pi (π) up to two decimal places is 3.14. Pi is a mathematical constant representing the ratio of a circle's circumference to its diameter and is commonly approximated as 3.14. Choices A, C, and D are incorrect as they do not match the standard approximation of pi up to two decimal places.

Correct Answer: D

Rationale: The runner left at 7:45 and returned at 10:00, which means he ran for 2 hours and 15 minutes (10:00 - 7:45). At an average speed of 6 mph, in 2.25 hours, he would have covered 6 mph * 2.25 hours = 13.5 miles. Therefore, the correct answer is 13.5 miles. Choices A, B, and C are incorrect because they incorrectly calculate the distance based on the time and speed provided in the question.

Correct Answer: A

Rationale: To add mixed numbers, first convert them to improper fractions. 6 3/4 = 27/4 and 8 1/6 = 49/6. Finding a common denominator, we get 27/4 + 49/6 = 81/12 + 98/12 = 179/12 = 14 & 11/12. Therefore, the correct answer is A. Choice B is incorrect as it does not simplify to the correct result. Choice C is in fraction form and not in mixed number form, making it incorrect. Choice D is not the correct sum of the given mixed numbers, so it is also incorrect.