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: D

Rationale: Compare and order the groups based on the fractions provided.

Correct Answer: C

Rationale: The baby's measured weight is the dependent variable as it depends on the time intervals.

Correct Answer: C

Rationale: To convert milliliters (mL) to liters (L), you divide by 1000 since 1000 mL is equivalent to 1 liter. Therefore, 2500 mL is equal to 2.5 liters (2500 mL · 1000 = 2.5 L). Choice A (0.25 L) is incorrect as it represents a conversion error by a factor of 10. Choice B (25 L) is incorrect as it incorrectly multiplies instead of dividing by 1000. Choice D (250 L) is incorrect as it overestimates the conversion by a factor of 100.

Correct Answer: D

Rationale: The percentage of blue gumballs is 35% (100% - 20% - 30% - 5% - 10% = 35%). If there are 120 gumballs, 35% of that is 42 blue gumballs. Since 5% are yellow gumballs, which is 6 gumballs, the difference between 42 blue gumballs and 6 yellow gumballs is 36 more blue gumballs. Therefore, the correct answer is 36. Choice A (48) is incorrect as it miscalculates the difference. Choice B (30) is incorrect as it does not consider the correct percentage of blue gumballs. Choice C (42) is incorrect as it miscalculates the difference between blue and yellow gumballs.