Math Problem Statement

Hubungan antara kompetensi (X) dan kinerja (Y) kita ambil sampel secara acak 10 orang. Tentukan: nilai korelasi r, berapa nilai b, berapa nilai a.

Solution

The image you uploaded provides data for calculating the correlation coefficient rr, the slope bb, and the intercept aa for a linear regression model. Let's break it down and calculate each:

Given Data:

  • X=[30,45,32,55,50,45,61,44,50,32]X = [30, 45, 32, 55, 50, 45, 61, 44, 50, 32]
  • Y=[9,30,12,24,15,54,22,17,5,17]Y = [9, 30, 12, 24, 15, 54, 22, 17, 5, 17]

Step 1: Calculating the correlation coefficient rr

The formula for the correlation coefficient rr is:

[ r = \frac{n(\sum xy) - (\sum x)(\sum y)}{\sqrt{[n \sum x^2 - (\sum x)^2][n \sum y^2 - (\sum y)^2]}} ]

Where:

  • nn is the number of data points
  • x\sum x is the sum of XX
  • y\sum y is the sum of YY
  • xy\sum xy is the sum of the products of corresponding XX and YY values
  • x2\sum x^2 is the sum of the squares of XX
  • y2\sum y^2 is the sum of the squares of YY

Step 2: Calculating the slope bb and intercept aa

The formulas for bb (slope) and aa (intercept) are:

b=n(xy)(x)(y)n(x2)(x)2b = \frac{n(\sum xy) - (\sum x)(\sum y)}{n(\sum x^2) - (\sum x)^2} a=yb(x)na = \frac{\sum y - b(\sum x)}{n}

Let me calculate these values for you now. numpy as np

Given data

X = np.array([30, 45, 32, 55, 50, 45, 61, 44, 50, 32]) Y = np.array([9, 30, 12, 24, 15, 54, 22, 17, 5, 17])

Number of data points

n = len(X)

Summing the required terms

sum_x = np.sum(X) sum_y = np.sum(Y) sum_x2 = np.sum(X2) sum_y2 = np.sum(Y2) sum_xy = np.sum(X * Y)

Calculating the correlation coefficient (r)

r = (n * sum_xy - sum_x * sum_y) / np.sqrt((n * sum_x2 - sum_x2) * (n * sum_y2 - sum_y2))

Calculating the slope (b) and intercept (a)

b = (n * sum_xy - sum_x * sum_y) / (n * sum_x2 - sum_x**2) a = (sum_y - b * sum_x) / n

r, b, aHere are the calculated values:

  • The correlation coefficient rr is approximately 0.2214.
  • The slope bb is approximately 0.2959.
  • The intercept aa is approximately 7.3601.

Would you like further clarification or details on any of these calculations?

Here are some related questions you might find useful:

  1. How does the correlation coefficient rr influence the relationship between variables?
  2. What is the interpretation of the slope bb in a linear regression model?
  3. How can you use the equation of the line Y=a+bXY = a + bX to predict YY from XX?
  4. How can you visualize the data and regression line?
  5. What are some possible reasons for a low correlation coefficient?

Tip: A positive correlation coefficient indicates that as XX increases, YY tends to increase as well, though the value here suggests only a weak relationship.

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Math Problem Analysis

Mathematical Concepts

Statistics
Linear Regression
Correlation Coefficient

Formulas

r = (n * Σxy - (Σx)(Σy)) / √[(n * Σx² - (Σx)²)(n * Σy² - (Σy)²)]
b = (n * Σxy - (Σx)(Σy)) / (n * Σx² - (Σx)²)
a = (Σy - b * Σx) / n

Theorems

Correlation coefficient
Linear regression model

Suitable Grade Level

Grades 10-12