What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

The standard deviation of the data set is 5.7 to the nearest tenth

Step-by-step explanation:

* Lets explain how to find the standard deviation

# Step 1: find the mean of the data set

∵ The mean = the sum of the data ÷ the number of the data

∵ The data set is 3 , 17 , 18 , 15 , 12 , 21 , 9

∵ Their sum = 3 + 17 + 18 + 15 + 12 + 21 + 9 = 95

∵ They are seven

∴ The mean = 95 ÷ 7 = 13.6

# Step 2: subtract the mean from each data and square the answer

∴ (3 - 13.6)² = 112.36

∴ (17 - 13.6)² = 11.56

∴ (18 - 13.6)² = 19.36

∴ (15 - 13.6)² = 1.96

∴ (12 - 13.6)² = 2.56

∴ (21 - 13.6)² = 54.76

∴ (9 - 13.6)² = 21.16

# Step 3: find the mean of these squared difference

∵ The mean = the sum of the data ÷ the number of the data

∵ The sum = 112.36 + 11.56 + 19.36 + 1.96 + 2.56 + 54.76 + 21.16 = 223.72

∴ The mean = 223.72 ÷ 7 = 31.96

# Step 4: the standard deviation is the square root of this mean

∴ The standard deviation = √(31.96) = 5.6533 ≅ 5.7

* The standard deviation of the data set is 5.7 to the nearest tenth

answer: there are x+184 pages in olivia's book.

step-by-step explanation:

let the total number of pages in the book which olive has already read be x.

then if olive has 184 pages left to read, then the total number of pages are in olive's book= pages she has read+pages she has left to read

therefore, the total number of pages in olivia's book=

hence, there are x+184 pages in olivia's book.

75

step-by-step explanation: