First, round each number to the nearest hundred thousand. 2,015,344 rounds to 2,000,000 because the digit in the ten thousands place (1) is less than 5. 1,489,550 rounds to 1,500,000 because the digit in the ten thousands place (8) is 5 or greater. Then, find the difference between the rounded numbers: \(2,000,000 - 1,500,000 = 500,000\).

To estimate the fuel efficiency, divide the miles traveled by the gallons of gasoline used. Round 357 miles to a number easily divisible by a rounded gallon amount. Round 11.8 gallons to 12 gallons. A compatible number for 357 that is close to it and divisible by 12 is 360. The estimated fuel efficiency is \(360 \div 12 = 30\) miles per gallon.

To find the average number of chips produced per day, divide the total number of chips by the number of days. Round 1,798,650 to 1,800,000 and 305 to 300 for easier calculation. Then divide: \(1,800,000 \div 300\). You can simplify this by canceling two zeros from each number: \(18,000 \div 3 = 6,000\). Approximately 6,000 chips were produced each day.

To estimate how many times higher the airplane is, divide the airplane's altitude by the mountain's height. Round 31,850 feet to 30,000 feet and 14,970 feet to 15,000 feet. The estimated ratio is \(30,000 \div 15,000 = 2\). The airplane is flying approximately 2 times higher than the mountain's peak.

First, estimate the area of the garden, then estimate the total cost. Round the dimensions of the garden to 25 meters and 10 meters. The estimated area is \(25 \text{ m} \times 10 \text{ m} = 250 \text{ m}^2\). The cost is $11 per square meter. To estimate the total cost, multiply the area by the price: \(250 \times \$11\). This can be calculated as \(250 \times 10 + 250 \times 1 = 2500 + 250 = \$2,750\).

To estimate the number of attendees, find approximately 74% of 8,124. Round 8,124 to 8,000. Round 74% to 75%, which is equivalent to the fraction \(\frac{3}{4}\). Calculate \(\frac{3}{4}\) of 8,000: \(\frac{3}{4} \times 8,000 = 3 \times(8,000 \div 4) = 3 \times 2,000 = 6,000\). Approximately 6,000 people are attending.

To estimate the total revenue for a week, first estimate the daily revenue and then multiply by 7. Round the number of widgets to 300 and the price to $50. The estimated daily revenue is \(300 \times \$50 = \$15,000\). The estimated weekly revenue is \(\$15,000 \times 7 = \$105,000\).

To estimate the number of lots, divide the total acreage by the acreage per lot. Round 119.7 acres to 120 acres and 0.48 acres to 0.5 acres. The problem becomes \(120 \div 0.5\). Dividing by 0.5 is the same as multiplying by 2. So, \(120 \times 2 = 240\). Approximately 240 lots can be created.

To find how many times larger Town A's population is, divide its population by Town B's population. First, round the populations to the nearest hundred thousand. Town A's population rounds to 800,000 and Town B's population rounds to 400,000. Then, divide: \(800,000 \div 400,000 = 2\). Town A is approximately 2 times larger than Town B.

When you encounter a problem involving distance, speed, and time, you're working with one of the fundamental relationships in physics: $$\text{Distance} = \text{Speed} \times \text{Time}$$. Rearranging this formula to solve for time gives us $$\text{Time} = \frac{\text{Distance}}{\text{Speed}}$$.

To find how long light takes to travel from the Sun to Earth, divide the distance by the speed of light: $$\frac{149,600,000 \text{ km}}{299,792 \text{ km/s}}$$. Since we're looking for an approximation, you can round these numbers to make the calculation easier: $$\frac{150,000,000}{300,000} = 500$$ seconds. This confirms answer D) 500 seconds.

Let's examine why the other answers represent common calculation errors. Answer A) 50 seconds results from incorrectly dividing by 3,000,000 instead of 300,000 – essentially missing a zero in the speed of light. Answer B) 50,000 seconds comes from dividing by only 3,000, which drastically underestimates the speed of light. Answer C) 5,000 seconds occurs when you divide by 30,000, again underestimating the speed by a factor of 10.

For distance-speed-time problems on standardized tests, always double-check your setup by ensuring your units will cancel properly. Here, kilometers divided by kilometers per second gives you seconds, which matches what the question asks for. Also, practice rounding strategically – 299,792 becomes 300,000, and 149,600,000 becomes 150,000,000 – to make mental math manageable while maintaining accuracy.