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**25. Create a word problem that involves operations with rational numbers in decimal form. Make sure you solve your problem . Then, have a classmate solve your problem. **

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My question: *On Friday, the temperature at Assiniboine Park in Winnipeg, MB, Canada, decreased by 2.3°C/h for 4 hours. It then decreased by 1.4°C/h for 2 and a half hours.*

*a) What was the total decrease in temperature?*

*b) What was the rate of decrease in temperature?*

**Solution:**

a) The time period can be represented by 4 and 2.5. The rates of the temperature decrease can be represented by -2.3 an -1.4.

*Method 1: Calculate in Stages*
You can represent the temperature decrease in the first 4 hours by:

**4 x (-2.3) = -9.2**

You can represent the total temperature decrease in the last 2 and a half hours by:

**2.5 x 1.4 = 3.5**

Add to determine the total temperature decrease.

**(-9.20) + 3.50 = -5.7**

*The total decrease in temperature was 5.7°C.*

__Method 2: Evaluate One Expression__
The total temperature decrease can be represented by:

**4 x (-2.3) + 2.5 x 1.4**

*Remember to use the order of operations*

B - brackets

E - exponents

D - division

M - multiplication

A - addition

S - subtraction

4 x (-2.3) + 2.5 x 1.4

= -9.2 + 3.5

= -5.7

b) The average rate of decrease in temperature is the total decrease divided by the total number of hours.

The total number of hours is 4 + 2.5 = 6.5

*The average rate of decrease in temperature was 1.08333...*
URL for picture: http://gogreenwinnipeg.com/wp-content/uploads/2010/06/assiniboine-park-winnipeg.jpg

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