Pearson Algebra 1 Common Core, 2011
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Pearson Algebra 1 Common Core, 2011 View details
3. Patterns and Nonlinear Functions
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Exercise 19 Page 251

Write the given radii in terms of feet.

Rule:
Number of Bags:


Practice makes perfect
We have a concrete forming tube with a volume where is the product of its length and the area of its circular base.
We are told that we can make of cement per bag. We need to write a rule to find number of bags of cement needed to fill a tube with feet and with either inches, inches, or inches.

Writing a Rule for the Volume of Any Tube

Since the volume of a tube is the product of its length and the area of its circular base with radius we can write a rule as follows.
This conversion came from the formula for the area of a circle.

Determining What Operation to Use

Now, we will write a formula for the number of bags of cement. Then, we will substitute the given radii into that formula. Assume that is the number of bags of cement. We know that one bag of cement can make and length of the tube we want to fill is Let's use this information!
The formula for the number of bags of cement is Since the formula is in terms of feet, let's rewrite the given radii in terms of feet. To do so, we will multiply each by the conversion factor of
Multiply by
Let's start with the inch radius calculation and substitute feet for in the formula.
We cannot use partial bags of cement, so should be rounded up to bags of cement. If we follow the same process for the other given radii, we have the following.
Formula Substitution Results Number of Bags