Solving Proportions

Have you ever played dominoes? In the standard set of dominoes,
7 out of 28 tiles, or one-fourth of the tiles, are doubles.

The ratios \(\frac{7}{28}\) and \(\frac{1}{4}\) are equivalent.
That is \(\frac{7}{28}\) = \(\frac{1}{4}\).
The equation \(\frac{7}{28}\) = \(\frac{1}{4}\) is an example of a proportion.
Continue reading Solving Proportions

Percents and Fractions

You’ll learn to express percents as fractions and vice versa. Knowing how to express a number in a different form can help you interpret a monthly budget.

You know that a 10 x 10 grid can be used to represent hundredths. Since the word percent means out of one hundred, you can also use a 10 x 10 grid to model percents.

Shade two fifths of the 10 x 10 grid. What percent have you modeled? Continue reading Percents and Fractions

Investigating Exponential Functions

Collect the Data
Step 1 Cut a sheet of notebook paper in half.
Step 2 Stack the two halves, one on top of the other.
Step 3 Make a table like the one below and record
the number of sheets of paper you have in the stack after one cut.
Step 4 Cut the two stacked sheets in half, placing the resulting pieces in a single stack. Record the number of sheets of paper in the new stack after 2 cuts.
Step 5 Continue cutting the stack in half, each time putting the resulting piles in a single stack and recording the number of sheets in the stack. Stop when the resulting stack is too thick to cut. Continue reading Investigating Exponential Functions

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Measures of Variability

In this lesson we learn the concept of  variability  and how to compute three measures of the variability of a data set.

Let’s start with two data sets:

Data set 1: 10,8,12,10,9,13,10,9,10

Data set 2: 16,7,10,3,12,6,10,17,4,15

The mean, median and mode of both data sets is the same: 10

The range is the difference between the largest and the smallest value in the data set.

For Data set 1 the range is 13-8=5 and for the second is 17-3=14

The range indicates the size of the smallest interval which contains all the data.  Less variability means a smaller range.

Since the range is based solely on the two most extreme values within the data set, if one of these is either exceptionally high or low (outlier) it will result in a range that is not typical of the variability within that data set.

The sample variance for data set 1 is 2.1 and for the second data set is 22.4

The sample standard deviation is 1.5 for the first data set and 5 for the second data set