[Question]Randy just turned 12 and started playing the piano. His friend Sheila told him about the 10,000-hour rule which says, after 10,000 hours of practice, you become an expert or master in your field. If Randy wants to become a piano expert before he is 20, how many hours a day will he need to practice if he practices every day, Monday – Friday, and takes two weeks off for vacation each year?
[Answer]Randy has 20 – 12 = 8 years until he is 20. He must practice 10,000 hours / 8 years = 1,250 hours a year to become an expert. There are 52 weeks in a year – 2 weeks of vacation Randy plans to take = 50 weeks of practice for Randy. Randy will practice Monday – Friday, which is 5 days a week, so 50 weeks x 5 days = 250 days of practice each year. Randy will need to practice 1250 hours / 250 days = 5 hours each day. The answer is 5.
Q: To make a shed in his backyard, Tom needs 1000 bricks. He can buy half of the bricks for 50% off of $.50. The other Half he needs to pay full price. How many dollars does Tom spend?
A: Tom can buy 1000 / 2 = 500 for half price. He will spend $.50 / 2 = $.25 on the half - priced bricks. Thus, he will spend 500 * $.25 = $125 on the half - priced bricks. He will spend 500 * $.50 = $250 on the full - priced bricks. Thus, he will spend $125 + $250 = $375 total. The answer is 375.
Question: Lizzie has half as many crayons as Bobbie. Bobbie has three times as many crayons as Billie. If Billie has 18 crayons, how many crayons does Lizzie have?
Answer: Bobbie has 18 * 3 = 54 crayons. Lizzie has 54 / 2 = 27 crayons. The answer is 27.
[Question]A man is returning home from work and trying to decide which route to take. His first route option includes 3 stoplights. This route will take him 10 minutes if all three lights are green, but each light that is red will add 3 minutes to the trip. The second route does not include any stoplights and takes 14 minutes. If the man chooses the first route, how much longer will his trip be if all 3 stoplights are red?
[Answer]If all 3 stoplights are red, the first route will take 10 + 3 * 3 = 19 minutes. Thus, the first route will take 19 - 14 = 5 minutes longer than the second route. The answer is 5.
Q: While cultivating a small farm, a farmer spent $50 on corn seeds, $35 on fertilizers and pesticides, and $15 on labor. After a successful harvest, he was able to gather 10 bags of corn. How much should he sell each bag, if he wants to make a profit of 10%?
A: His total expenditure so far is $50 + $35 + $15 = $100. To make a profit of 10%, he has to make a total of $100 + ($100 * (10 / 100) = $110 from sales. To make $110 from the sales of 10 bags, each bag should cost $110 / 10 = $11. The answer is 11.
Question: Sam invested $10,000 and earned 20% interest compounded for 3 years. He then invested more until he had three times as much invested. The next year, he got a 15% return on his investment. How much money does he have now?
Answer:
After one year, Sam had $10,000 * 1.2 = $12,000. After two years, he had $12,000 * 1.2 = $14,400. After the third year, he had $14,400 * 1.2 = $17,280. He then invested more money until he had 3 * $17,280 = $51,840. The first year after that, he had $51,840 * 1.15 = $59,616. The answer is 59616.