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Finding the Fourth Proportional to 820, 1,131.68 and 470.72

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Solution

The fourth proportional to 820, 1,131.68 and 470.72 is: 649.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    820 : 1,131.68 = 470.72 : x
  2. Step 2: Convert to fraction form
    820/1,131.68 = 470.72/x
  3. Step 3: Cross multiply
    820x = 1,131.68 × 470.72
  4. Step 4: Simplify right side
    820x = 532,704.41
  5. Step 5: Solve for x
    x = 532,704.41/820
  6. Step 6: Final answer
    x = 649.64

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.