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.
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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