A train travels 270 miles in 3 hours. At the same rate, how many additional hours would it take to travel an additional 180 miles?
Let's think: The rate is 270 / 3 = 90 mph. Then it takes an additional 180 / 90 = 2 hours.. The answer is: 2.

If one fourth of the engines are defective, and there are 5 batches of 80 engines each. How many engines are not defective?
Let's think: There are 80 * 5 = 400 engines in total. 400 / 4 = 100 of the engines are defective. 400 - 100 = 300 of the engines are not defective.. The answer is: 300.

Lagoon island is populated by alligators. Half the alligators are male. The rest are female. Among the females, 40% are juveniles. There are 15 adult females. How many male alligators are there?
Let's think: 60% of female alligators are adults because 100 - 40 = 60. There are 25 female alligators because 15 / .6 = 25. There are 50 alligators in total because 25 / .5 = 50. There are 25 male alligators because 50 / 2 = 25.. The answer is: 25.

Mark was caught speeding and the judge wants to make an example out of him. The base fine for speeding is $50 but additional penalties apply in this case. The fine is increased by $2 for every mile per hour Mark was going over the speed limit. He was going 75 miles per hour in a 30 mile per hour zone. The fine is also doubled because he was in a school zone. Finally, the judge makes Mark pay $300 in court costs and he also has to pay his lawyer $80/hour for three hours of work. How much does Mark owe for this speeding ticket?
Let's think:
First figure out how many miles over the speed limit Mark was going: 75 mph - 30 mph = 45 mph. Now figure out how much the per - mile fine is: $2 / mph * 45 mph = $90. Now add that amount to the base fine: $90 + $50 = $140. Now double that amount for being in a school zone: $140 * 2 = $280. Now figure out how much Mark owes his lawyer: $80 / hour * 3 hours = $240. Now add the court costs, lawyer fees and fine: $240 + $300 + $280 = $820.. The answer is: 820.