Step-1

Title: Statistics

Grade: Core-SAT3 Lesson: S8-P2

Explanation: Hello Students, time to practice and review the steps for the problem.

Discussion: Step1 Step2 Step3 Step4 Step5

Lesson Steps

Step Type Explanation Answer

1

Problem

Calculate the standard deviation for the sample weights (in grams):
62.3, 74.1, 51.8, 23.5, 25.2, 40.9, and 93.2.

2

Step

Given weights (in grams)

62.3, 74.1, 51.8, 23.5, 25.2, 40.9, and 93.2

3

Step

Calculate the Mean (Average)
Sum up all the weights and then divide by the number of weights

\$"Mean" = (62.3 + 74.1 + 51.8 + 23.5 + 25.2 + 40.9 + 93.2)/7\$
\$"Mean" = 371/7\$ = 53

4

Step

The mean weight is 52.85 grams

5

Step

Calculate the Absolute Deviations from the Mean
Find the absolute deviation of each weight from the mean

\$\∣62.3 − 53\∣ = 9.3\$
\$\∣74.1 - 53\∣ = 21.1\$
\$\∣51.8 - 53\∣ = 1.2\$
\$\∣23.5 - 53\∣ = 29.5 \$
\$\∣25.2 - 53\∣ = 27.8\$
\$\∣40.9 - 53\∣ = 12.1\$
\$\∣93.2 - 53\∣ = 40.2\$

6

Step

obtain the squares of each deviation

\$(9.3)^2\$ = 86.49
\$(21.1)^2\$ = 445.21
\$(1.2)^2\$ = 1.44
\$(29.5)^2\$ = 870.25
\$(27.8)^2\$ = 772.84
\$(12.1)^2\$ = 146.41
\$(40.2)^2\$ = 1616.04

7

Step

Sum up the squared deviations and then divide by the number of weights by reducing which is
(n - 1) to find the mean of squared deviations

\$"Mean" = (86.49 + 445.21 + 1.44 + 870.25 + 772.84 + 146.41 + 1616.040) / (7 - 1)\$
\$"Mean" = 3938.68/6\$ = 656.44

8

Step

calculate the square root of mean of squared deviations

\$sqrt(656.44)\$

9

Step

Therefore, the Standard Deviation (SD) for the weights is approximately 25.61cm.

10

Choice.A

This option is correct because 25.61 is the accurate standard deviation of the given weights in grams

25.61

11

Choice.B

This option is incorrect but, 25.09 is closer to the actual result of given weights but it is not accurate SD which is 25.61 grams

25.09

12

Choice.C

This option is incorrect because 24.98 is slightly lower than the actual standard deviation of the given weights in grams

24.98

13

Choice.D

This option is incorrect because 24.37 does not match the actual standard deviation of the given data

24.37

14

Answer

Option

A

15

Sumup

Can you summarize what you’ve understood in the above steps?


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