Answer:
Step-by-step explanation:
Answer:
The standard deviation of the data set is
.
Step-by-step explanation:
The Standard Deviation is a measure of how spread out numbers are. Its symbol is σ (the greek letter sigma)
To find the standard deviation of the following data set

we use the following formula

Step 1: Find the mean
.
The mean of a data set is the sum of the terms divided by the total number of terms. Using math notation we have:


Step 2: Create the below table.
Step 3: Find the sum of numbers in the last column to get.

Step 4: Calculate σ using the above formula.

(x-9) (x+2)=x²+2x-9x-18=x²-7x-18
The sum of 4.35 and -5.66