## Monday, October 12, 2009

### Coin Math

HAPPY THANKSGIVING EVERYONE!!!

First, I'm going to answer two questions about the money jar using math.

1. What graph would be best for displaying the data?

I think that it depends on what data you are displaying. For example, if you are trying to represent how many of each coin there is in the jar, a circle graph or a bar graph would be best because they are good for grouping data. However, if you were trying to represent how long it took to fill the jar, a line graph would be the best to use because they are good for displaying the changes in data over time.

2. What is the most common coin in the jar?

Since the money in the jar came in rolls, my estimate would be that the coin with the most pieces in one roll would be the most common. In her scribe post, Brianna said that there were 50 coins in a roll of pennies, 40 coins in a roll of nickels, 50 coins in a roll of dimes, and 40 coins in a roll of quarters. Looking at this data, pennies and dimes have the same amount of coins in their rolls. My estimate is that there are more pennies because they are 10 times cheaper than dimes.

Now that I've answered the two questions, it's time to answer the the BIG one that Mr. Harbeck assigned all of us.

How many coins are in the jar?

Ok, first of all let's see how much money one roll of each coin adds up to.

Pennies: \$0.50 (50 coins)

Nickels: \$2.00 (40 coins)

Dimes: \$5.00 (50 coins)

Quarters: \$10.00 (40 coins)

When added together, one roll of each type of coin equals \$17.50. We are trying to make \$100.00. First, lets make \$17.50 into an easier number. another roll of pennies would make \$18.00. Plus another roll of nickels would make \$20.00, which can be divided into \$100.00.

So far, we have \$20.00. We have used 2 rolls of pennies, 2 rolls of nickels, one roll of dimes, and one roll of quarters. (270 coins). This means that 2 rolls of pennies, 2 rolls of nickels, one roll of dimes and one roll of quarters is one set. Since 20 multiplied by 5 equals 100, that means we need 5 sets to get the answer.

Pennies: 100 x 5 = 500

Nickels: 80 x 5 = 400

Dimes: 50 x 5 = 250

Quarters: 40 x 5 = 200

500+
400+
250+
200=

1 350 coins!

Conclusion:
There are 1 350 coins in the jar of \$100.00.

PART 2:

Today in class, we found out that there are actually 1 280 coins in the American jar. We also found out that, if it was a Canadian jar using loonies and toonies there would be 370 coins. The American jar is 3/4 full, but we don't know how full the Canadian jar is. Our assignments are to figure out how full the Canadian jar is, and to figure out how long it would take to fill each jar if we started on January 1st of 2010.

I'm going to start with the hard question first. How full is the Canadian jar? Well, we know that the American jar has 1 280 coins, and it is 3/4 full. That means that the Canadian jar is going to be less than 3/4 full because it has less coins. However, we need more info right? So, lets divide 1 280 in half.

1 280/2= 640. This means that the Canadian jar is less than 1/2 full.

1 280/4= 320. This means that the Canadian jar is more than 1/4 full.

A fraction between these two would be 3/8.

1 280/8= 160.

160 x 3= 480. This means that the Canadian jar is less than 3/8 full.

A fraction in between these two would be 5/16.

1 280/ 16= 80

80 x 5= 400. This means that the Canadian jar is less than 5/16 full.

A fraction between 1/4 and 5/16 is 9/32.

1 280/32= 40.

40 x 9= 360. This is as close as I can get to 370, but here is a picture representing how full each jar is:

Now, on to the easier questions.

If you dropped one coin in the Canadian jar every day, starting on January 1st, 2010 you would reach \$100.00 on January 10th, 1011. Because there are 365 days in a year. On the 365th day, you would have 5 coins left and it would be January 1st. Therefore, you would finish on January 5th.

If you dropped one coin in the American jar every day, starting on January 1st, 2010 you would reach \$100.00 on July 9th, 2013. Because 365 x 2= 730. Those are the first two years. The next year is a leap year so you add 361 days to get 1091. That is the 3rd year. Then, you add 199 more days to get to 1 280. 199 days from January 1st of 2133 is July 9, 2133.

THANKS FOR READING MY POST! I apologize if it doesn't make sense but I tried my best :)

PLEASE COMMENT SO I CAN MAKE IT BETTER THANKS!!!

~Laura :)

1. Great job Laura

2. good job!it's clear and easy to uderstand

3. Thanks! Sorry I couldn't figure out the actual fraction for the Canadian jar. :)

4. Laura i really like the way you explained no.1 setp by step..it's very understandable
KEEP UP THE GOOD WORK:)

5. good job laura, very understandable with the step by step lecture

much better then one long one