Math Problem Statement

Soal 3: Tentukan Mean/Rerata dari histogram yang menunjukkan interval kelas dan frekuensi.

Solution

To solve the problem and find the mean (rata-rata) from the histogram provided, follow these steps:

Step 1: Identify the Class Intervals and Frequencies

From the histogram, we can observe the class intervals and their corresponding frequencies:

  • 40–43: Frequency = 5
  • 43–46: Frequency = 17
  • 46–49: Frequency = 14
  • 49–52: Frequency = 10
  • 52–55: Frequency = 4

Step 2: Find the Midpoints of Each Class Interval

To find the mean, we first need to calculate the midpoints (xix_i) of each class interval:

  • Midpoint of 40–43: 40+432=41.5\frac{40 + 43}{2} = 41.5
  • Midpoint of 43–46: 43+462=44.5\frac{43 + 46}{2} = 44.5
  • Midpoint of 46–49: 46+492=47.5\frac{46 + 49}{2} = 47.5
  • Midpoint of 49–52: 49+522=50.5\frac{49 + 52}{2} = 50.5
  • Midpoint of 52–55: 52+552=53.5\frac{52 + 55}{2} = 53.5

Step 3: Calculate the Mean

The mean can be calculated using the formula:

Mean=(fi×xi)fi\text{Mean} = \frac{\sum (f_i \times x_i)}{\sum f_i}

Where fif_i is the frequency and xix_i is the midpoint for each class interval.

  • (41.5×5)=207.5(41.5 \times 5) = 207.5
  • (44.5×17)=756.5(44.5 \times 17) = 756.5
  • (47.5×14)=665(47.5 \times 14) = 665
  • (50.5×10)=505(50.5 \times 10) = 505
  • (53.5×4)=214(53.5 \times 4) = 214

Step 4: Sum of the Products and Frequencies

Sum of products fi×xif_i \times x_i: 207.5+756.5+665+505+214=2348207.5 + 756.5 + 665 + 505 + 214 = 2348

Sum of frequencies fi\sum f_i: 5+17+14+10+4=505 + 17 + 14 + 10 + 4 = 50

Step 5: Final Calculation

Now, calculate the mean: Mean=234850=46.96\text{Mean} = \frac{2348}{50} = 46.96

Answer:

The mean (rata-rata) is 46.96.

Would you like more details or have any questions?


Here are five related questions to expand on this concept:

  1. How would the mean change if the frequency of the class interval 43-46 were doubled?
  2. What is the median class interval, and how do you find it from this histogram?
  3. How does the mean compare to the mode in this distribution?
  4. How would you calculate the variance and standard deviation from this data?
  5. What is the impact on the mean if an outlier is added to this data set?

Tip: Remember that the mean is sensitive to extreme values (outliers), while the median is more robust in such cases.

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Math Problem Analysis

Mathematical Concepts

Statistics
Mean Calculation
Frequency Distribution

Formulas

Mean = (Σ f_i * x_i) / Σ f_i
Midpoint = (Lower Bound + Upper Bound) / 2

Theorems

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Suitable Grade Level

Grades 9-11