Correct Answer: C

Rationale: Let Lulu's sister's age be x. According to the given information, x = 15 (cousin's age) + 7 = 22. So, Lulu's sister is 22 years old. Since Lulu is 5 years younger than her sister, Lulu's age is 22 - 5 = 17. Therefore, Lulu is 17 years old. Choices A, B, and D are incorrect because they do not correspond to the calculations based on the information provided in the question.

Correct Answer: D

Rationale: To calculate the time it takes to travel a certain distance, we can use the formula Time = Distance / Speed. In this case, the helicopter is flying at 80 mph and needs to travel 140 miles. Therefore, Time = 140 miles / 80 mph = 1.75 hours or 1 hour and 45 minutes. So, the correct answer is D. 1 hour 45 minutes. Choices A, B, and C are incorrect as they do not represent the accurate time it takes for the helicopter to cover the 140-mile distance at 80 mph.

Correct Answer: A

Rationale: To find 60% of 90, you multiply 90 by 0.60 (which is the decimal form of 60%). So, 90 * 0.60 = 54. Therefore, 60% of 90 is 54. Choice A is correct. Choice B, C, and D are incorrect as they do not reflect the correct calculation for finding 60% of 90.

Correct Answer: A

Rationale: To find the sum of the numbers 34 + 74 + 37, add them together: 34 + 74 + 37 = 145. Therefore, the correct answer is A. Choice B (155) is incorrect as it results from adding 34 + 74 + 37 incorrectly. Choice C (154) is incorrect as it is the result of adding the first two numbers correctly, but missing the addition of the third number. Choice D (135) is incorrect as it is the result of a calculation error, possibly adding the numbers in a different order.

Correct Answer: D

Rationale: To find the result of multiplying 6 by 55, you perform the operation 6 55, which equals 330. To express this product in decimal form, you place the decimal point one place from the right, resulting in 3.3. Therefore, the correct answer is D (3.3). Choices A, B, and C are incorrect as they do not represent the correct decimal equivalent of the multiplication of 6 and 55.