First, find the car's fuel efficiency in miles per gallon (the unit rate). Efficiency = Total miles / Total gallons = 450 miles / 15 gallons = 30 miles per gallon. Then, multiply this rate by the amount of gas currently in the tank. Distance = 30 miles/gallon × 4 gallons = 120 miles.

First, find the total distance the snail moves in one hour (60 minutes) in feet. Distance in feet = 2 feet/minute × 60 minutes = 120 feet. Next, convert this distance from feet to yards using the given conversion factor. Distance in yards = 120 feet / 3 feet/yard = 40 yards.

First, find the drip rate in milliliters per second: 5 mL / 10 seconds = 0.5 mL per second. Next, find the total seconds in an hour: 60 seconds/minute × 60 minutes/hour = 3,600 seconds. Calculate the total milliliters wasted: 0.5 mL/second × 3,600 seconds = 1,800 milliliters. Finally, convert milliliters to liters: 1,800 mL / 1,000 mL/liter = 1.8 liters.

First, find the rate of punch production: 18 liters / 6 minutes = 3 liters per minute. In 10 minutes, the machine makes 3 L/min × 10 min = 30 liters of punch. The recipe has 2+1=3 total parts. The fraction of cranberry juice is 2/3. So, the amount of cranberry juice is (2/3) × 30 liters = 20 liters.

First, calculate the cost per pound (the unit rate). Cost per pound = Total cost / Number of pounds = $7.50 / 5 pounds = $1.50 per pound. Then, multiply this unit rate by the desired number of pounds to find the total cost. Cost for 8 pounds = $1.50/pound × 8 pounds = $12.00.

First, calculate the total growth over 15 days. The rate is 2 cm per 3 days. The number of 3-day periods in 15 days is 15 / 3 = 5. So, the total growth is 5 × 2 cm = 10 cm. Then, add this growth to the seedling's initial height: 10 cm (initial) + 10 cm (growth) = 20 cm.

This question tests the ability to solve measurement problems using unit rates on the ISEE Lower Level. Understanding unit rates involves calculating how one unit relates to another, such as miles per hour or cost per item. In this specific problem, students must apply the given unit rate of 45 miles per hour to determine how long it takes to travel 90 miles. The correct answer, Choice B (2 hours), is calculated by dividing the total distance (90 miles) by the speed (45 miles per hour): 90 ÷ 45 = 2 hours, which shows a correct understanding of applying unit rates. Choice C (45 hours) is incorrect because it reflects a common student error of using the speed as the answer without performing any calculation, while Choice A (1 hour) might result from incorrectly halving the distance without considering the speed. To help students, encourage them to practice identifying unit rates in various contexts and performing calculations step-by-step. Teach students to double-check units and ensure each calculation step logically follows from the last, remembering that time = distance ÷ speed.

This is a two-step problem. First, calculate the total weight of the metal block. Weight = Density × Volume = 5 grams/cm³ × 40 cm³ = 200 grams. Second, calculate the total cost using the price per gram. Cost = Total weight × Price per gram = 200 grams × $2/gram = $400.

First, find Samantha's typing speed in words per minute. Speed = 200 words / 4 minutes = 50 words per minute. Then, divide the total number of words in the essay by her speed to find the time required. Time = 1,500 words / 50 words per minute = 30 minutes.

First, find the unit rate of ink used per poster. Rate = 3 pounds / 600 posters = 0.005 pounds per poster. Then, multiply this rate by the new number of posters. Ink needed = 0.005 pounds/poster × 1,000 posters = 5 pounds. Alternatively, find posters per pound: 600/3 = 200 posters per pound. For 1,000 posters, you need 1,000/200 = 5 pounds.