# Statistics and Probability Formulas You Need to Know for the HiSET® Math Test

You will be given some formulas during the HiSET® Test. However, that won’t be enough, especially for statistics and probability questions. As you probably know, there are many formulas that you need to use for those items on the test, and even though they are quite easy to remember, it is important that you know which ones you’ll need! That’s why we’ve compiled the most important Statistics and Probability formulas you need to know for the HiSET® Test! Use them to solve the free sample questions we have for you!

We also have two other charts of formulas that are not given to you during the test and a preview of the chart of formulas you will be given during the HiSET Math Test session.

Geometry Formulas You Need to Know for the HiSET® Math Test

Algebra Formulas You Need to Know for the HiSET® Math Test

Formulas You Will Be Given for the HiSET® Math Test

## Statistics and Probability Formulas for the HiSET® Math Test

Category Formula Symbols Comment
Probability and
Statistics
$$\overline{x} = \dfrac{\Sigma x_i}{n}$$ $$\overline{x}$$ = sample mean
$$x_i$$ = value of each measurement
$$n$$ = number of measurements

Probability and
Statistics
$$Md = (\frac{n+1}{2})^{th} \ term$$ $$Md$$ = Median
$$n$$ = number of measurements (odd)

Probability and
Statistics
$$Md = \dfrac{(\frac{n}{2})^{th} \ term + (\frac{n}{2} +1)^{th} \ term}{2}$$ $$Md$$ = Median
$$n$$ = number of measurements (even)

Probability and
Statistics
$$s = \sqrt{\dfrac{\Sigma(x_i- \overline{x})^2}{ (n-1)}}$$ $$s$$ = Standard Deviation
$$\overline{x}$$ = mean
$$x_i$$ = value of each measurement
$$n$$ = number of measurements

Probability and
Statistics
$$V = s^2$$ $$V$$ = Variance
$$s$$ = Standard Deviation

Probability and
Statistics
$$CV = RSD = 100 \cdot \frac{s}{\overline{x}}$$ $$CV$$ = Coefficient of Variation
$$RSD$$ = Relative Standard Deviation
$$s$$ = Standard Deviation
$$\overline{x}$$ = mean

Probability and
Statistics
$$p= \frac{d}{t}$$ $$p$$ = Probability of an Event
$$d$$ = Number of Ways Desired Event Can Occur
$$t$$ = Total Number of Possible Events

Probability and
Statistics
$$P(A \cup B) = P(A) + P(B) - P(A \cap B)$$ $$P(A \cup B)$$ = Probability of A or B
$$P(A)$$ = Probability of A
$$P(B)$$ = Probability of B
$$P(A \cap B)$$ = Probability of A and B
$$P(A \cap B) = P(A) \cdot P(B)$$ $$P(A \cap B)$$ = Probability of A and B
$$P(A)$$ = Probability of A
$$P(B)$$ = Probability of B
$$P(A \cap B) = 0$$ $$P(A \cap B)$$ = Probability of A and B Mutually Exclusive Events