2. If a 50-gallon water heater leaks.4 gallons of water every 17 minutes, how long until it is completely empty?

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Blue Multiply Decimals Whole Numbers 1. What is a better buy, a 2 wide roll of tape that is 55 yards long and sells for $5.75, or a 1.75 wide roll that is 48 yards long and sells for $5.25? 2. If a 50-gallon water heater leaks.

1 Blue Multiply Decimals Whole Numbers 1. What is a better buy, a 2 wide roll of tape that is 55 yards long and sells for $5.75, or a 1.75 wide roll that is 48 yards long and sells for $5.25? 2. If a 50-gallon water heater leaks.4 gallons of water every 17 minutes, how long until it is completely empty? 3. Write an expression that includes a product of decimals. Show how you would estimate the answer. 4. Two people estimate the product $1.99 & 8.5 Is it necessary that they get the same estimate? Explain You estimate to be 5, but your friend estimates the quotient to be 7. Explain 3.75 how the 2 estimates can be different and yet both are reasonable. 6. Suppose you visit Mexico, and you want to estimate the cost of a jacket in U.S. dollars. The jacket costs 1,258 pesos. The exchange rate is $.117 = 1 peso. a. How many pesos is equivalent to U.S. $1.00? b. What is the 1,258 peso jacket worth in U.S. Dollars? c. Estimate the price of a shirt that costs 326 pesos and a souvenir that costs 45 pesos. 7. You can estimate a temperature in degrees Fahrenheit using the formula F = 2C + 30 where C represents the temperature in degrees Celsius (ºC). What is the approximate temperature in degrees Fahrenheit when it is: a ºC In each question, write down the answer together with the decimal calculation you used to work it out. The first one has been done for you. 8. A length of wood measures 3.48 m. It is then split into four equal pieces. What is the length of each piece? 9. How many 45 cents stamps can you buy for $30.60?

2 10. Debbie buys 8 bags of crisps for $9.20. What does one bag cost? litres of petrol cost $ How much does 1 litre of petrol cost? 12. If 5 rabbits eat 12.5 lettuces in 5 days, how many lettuces will 10 rabbits eat in 10 days? The answer is NOT 25! 13. Giving with Grapefruit Cassie bought grapefruit for a charity breakfast. She purchased 5 boxes of large ruby red organic grapefruit, with a dozen grapefruit in each box. The supplier gave her a great price of $19 per box to support the charity. The charity is tax exempt, so Cassie won't have to pay any more than the cost per box. At the breakfast, the grapefruit will sell for $1.50 per half. How much profit will Cassie make for the charity if she sells all the grapefruit halves? Extra: Cassie realizes that she might not sell all the grapefruit halves. How many does she need to sell to avoid losing money? 14. What a Move! We hired a company to help us move the second week in October miles from Annandale, Virginia to Springfield, Virginia. In the estimate, we were quoted $160 per hour for a five-man team plus the standard one hour travel time. We also had a $40 charge for moving the piano, and we opted to pay $150 for additional insurance. Our final bill came to $1870. How many hours did the five-man team work? How many man-hours total? 15. The cost of diesel is 63 cents/liter. How much will 2750 ml cost? 16. Liam's monthly income is $1600. He spends 0.05 of it on transport, 0.2 of it on rent, 0.3 of it on food and 0.25 of the rest on others. If he saves the remaining amount, how much does he save in a month? 17. Winnie's monthly income is $1600. She spends 0.05 of it on transport, 0.2 of it on rent, 0.3 of it on food and 0.25 of the rest on the other things. If she saves the rest of her income, how much money can he save in ¼ of a year? 18. After giving 10% of her beads to Phoebe, and 0.15 of them to Seung-Hee, and 0.2 of the remainder to Pari, Alex had 48 beads left. How many more beads did Alex give to Pari than to Phoebe? 19. Marco had 16.2 liters of gas in his car tank when he started on his journey. After traveling for some time, he had only 3.6 liters of gas left and he refilled the tank with $30 worth of gas at $1 per liter. At the end of his journey his gas level was 2.8 liters. Throughout the journey, he traveled 1 km with every 0.2 liters of gas. Find the total distance he covered.

3 20. Hee Bin has 0.4 times as many songs on his MP3 player as Chris, and 0.5 times as many songs as Daniel. If the 3 boys have 330 songs altogether, how many more songs does Chris have than Daniel? Solutions 1. 2 wide roll The 2 wide roll is 55 x 36 inches in a yard = 1980 inches The area of the 2 roll is 2 inches x 1980 inches = 3960 square inches The cost for each square inch is $ = cents The 1.75 wide roll is 48 x 36 inches in a yard = 1728 inches long The area of the 1.75 roll is 1.75 inches x 1728 = 3024 square inches The cost for each square inch is $ = cents hours and 25 minutes How many.4 gallos parts are in 50 gallos? 50.4 = 125 parts 17 minutes for each part to leak out. 125 x 17 minutes per part = 2125 minutes for the tank to empty = 35 and 25 minutes x 1.97 is a expression. To estimate the answer I would round to the nearest whole number in this case 3 x 2 = No. Some people may estimate to the nearest whole number $2 x 9 = $18. Other would estimate $2 x 8.5 and get $17. The second estimate is closer to the actual answer, but both estimates would be acceptable divided by 4 is approximately divided by 3 is rounds up to 4, so 5 is a reasonable solution. If you ignore the digits after the decimal, 21 divided by 3 is a. b. c x = 8.55 pesos 1peso xpeso 1 x x = $ pesos 1258pesos $38.13 (shirt) $ 5.26 (souvenir) Total $ ºF m stamps

4 10. $ $ Giving with Grapefruit If Cassie sells all the grapefruit halves, she will have $85.00 for a profit. If Cassie only wants to avoid losing money, she will have to only sell 64 halves. This will give her a dollar extra. First,I did 12(grapefruits in each box) times 5(boxes Cassie bought). The total grapefruits in all was 60. To figure out the cost, I did $19 (per box)x 5( boxes bought)=$95 spent. 60 grapefruits x 2(because she sold these grapefruits in halves) = 120 halves. Each half was $1.50 x 120 halves= $ To figure out her profit, I subtracted the cost of the grapefruits ($ $95.00=$85.00). I then knew Cassie's profit was $ To figure out the extra, I tried different numbers of halves and multiplied it by $1.50. My goal was to get $ If Cassie sold 63 grapefruit halves it gave her $94.50 which was not enough. She had to sell 64 grapefruit halves to get back all of her $ This gave her a profit of $1.00 (64 x $1.50= $96.00) Extra. We knew from doing the last problem that she spent $95 on the grapefruit. So, our first thought was to divide 1.50 into 95. It didn't fit. So, we decided to increase 95 by 1.50, because 95 alone is not divisible by So, we then divided 1.50 into Still didn't fit. But, we then decided to take.5 off of 96.5, to get a result of 96. We then divided 1.50 into 96 for a answer of 64 grapefruit halves. 14. What a Move! The five-man team of moving men worked for 9 hours and 30 minutes,and 47 manhours and thirty man-minutes. First, I figured out the sum on the additional money charged to 'me' for moving the piano($40) and additional insurance ($150), which added up to $190. I subracted that from the final bill of $1870, because that was just additional charge, and not time that the work men worked; that equaled $1680. I knew that the challenge said that 'we' were told that the charge for each hour that the five-man team worked would cost 'us' $160. So, I divided the $1680 by 160 to get the number of hours that the work men worked for, because the product of the number of hours that they worked and the price for each hour had to equal $1680, because that was the final charge for the number of hours that the workmen worked. I got the number I then converted that number into hours, and I got 10 hours and 30 minutes. Then, I subtracted one hour from 10 hours and 30 minutes, because in the challenge it said that 'I' paid for the standard one hour traveling time, and I

5 got 9 hours and 30 minutes. To finish up this challenge, I converted nine hours and thirty minutes to 9.5 so that I could multiply it by five in order to figure out how many hours one man would have worked, and got I converted that into hours and got 47 hours and 30 minutes $ km 20. Chris = 150, Daniel = 120.

Challenge Math (Second Edition): Hickory Grove Press, 2005. 13-14 The Math Forum @ Drexel (http://mathforum.

6 Bibliography Information Teachers attempted to cite the sources for the problems included in this problem set. In some cases, sources may not have been known. Problems Bibliography Information 1-2 Zaccaro, Edward. Challenge Math (Second Edition): Hickory Grove Press, The Math Drexel ( Lee, Joseph D. Primary Mathematics 6: Challenging Word Problems. Singapore: EPB Pan Pacific, 2006.

Estimating with Decimals

Name Date Class Practice A Estimating with Decimals Round to the nearest whole number. 1. 4.23 2. 1.91 3. 10.75 4. 5.88 5. 12.07 6. 18.70 Estimate by rounding. 7. 8.4 15.9 8. 3.45 5.34 9. 9.36 7.542 10.