All Algebra II Resources
Example Questions
Example Question #433 : Basic Statistics
If varies indirectly with and when , due to the effect of a constant, what is the value of when ?
Since varies indirectly with ,
1. Solve for when and .
2. Use the equation you found to solve for when .
Example Question #2 : Variable Relationships
varies directly with . If , what is if ?
1. Since varies directly with :
with K being some constant.
2. Solve for K using the x and y values given:
3. Use the equation you solved for to find the value of y:
Example Question #4 : Identifying Variable Relationships
varies inversely with . If , then what is equal to when ?
1. Since varies indirectly with :
2. Use the given x and y values to determine the value of K:
3. Using the equation along with the value of K, find the value of y when x=5:
Example Question #5 : Identifying Variable Relationships
varies directly with and when . What is when ?
1. Since varies directly with :
2. Use the values given for x and y to solve for K:
3. Use your new equation with the K you solved for to solve for y when x=27:
Example Question #441 : Basic Statistics
varies inversely with . When . What is the value of when ?
1. Since y varies indirectly with :
2. Solve for K using the x and y values given:
3. Using the equation you created by solving for K, find y when x=100:
Example Question #1 : Interpolations
Given the two following points, use interpolation to determine the best estimate for the value
,
Using our two known points, we can use interpolation to determine the value at any point between them with the following formula:
Where is our first given point, is our second given point, and is the point we want to find. We know our two given points, as well as the x value of our unknown point, so now all we must do is plug in all of our known values and solve for y, our only unknown:
Example Question #1 : Interpolations
The output of a factory in units per day versus the number of employees working is plotted on the graph below, with the following data points collected:
(Workers, Units of output per day):
Assuming a linear relationship, interpolate to find how many units will be made per day if workers are present.
We want to do a linear interpolation since the relationship between workers and units can be assumed to be linear. This means there is a constant slope between the points, so the slope between two known points will be equal to the slope between the point we are trying to find and some known point. This is expressed in the relation:
,
where and are the points we want to find and and are known. We choose the known points to be those that are just to the left and right of the point we are trying to find,
and .
Plugging these into our interpolation formula and knowing , we can find , the units output per day.
.
Simplifying and rearranging to solve for :
.
So there are units produced when the number of workers is .
Example Question #1 : Interpolations
Given the points and , use linear interpolation to find the value of when .
Use the formula for interpolation to determine the value of y:
We will use (30, 51) as our x2 and y2 and (20, 36) as our x1 and y1 and we will solve for y using 26.5 for x.
Example Question #1 : Interpolations
Given and use linear interpolation to find when .
Use the formula for interpolation:
We will use (30, 15) as x2 and y2, (15, 10) as x1 and y1, and solve for y when x=17.9:
Example Question #5 : Interpolations
Mary measures her height every year on her birthday, starting at 11 until she turns 16. She wants to make a table with all the information gathered, but discovers she lost the piece of paper on which she wrote her height down on her 14th birthday. Her incomplete table looks like this:
Age (years) | Height (inches) |
11 | 47.5 |
12 | 50.25 |
13 | 53 |
14 | ? |
15 | 58.5 |
16 | 61.25 |
Using the method of linear interpolation, which of the following is the closest estimate of Mary's height on her 14th birthday?
Not enough information given in the problem.
Using linear interpolation means that we draw a line between the points on our data set and use that line to estimate a value that lies between two data points; in this case, we have the data from Mary's 13th and 15th birthdays, so we can describe a line between those two points and estimate her height at 14. Our line will be written in slope-intercept form:
Where the variable represents Mary's Age in years and the variable represents her height in inches. First, we need to find the slope. Using 2 points on our table and as point 1 and point 2, respectively, we plug these values into our slope formula:
Next, we find the y-intercept by plugging in our slope (which we just found) and a point from our table (we'll stick with ) and solving for :
Simplify:
Subtract 35.75 from both sides to solve for :
The equation of our interpolation line is:
So, to get an estimate of Mary's height on her 14th birthday, we plug in and solve for :
Our estimate of Mary's height at is