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Finding the Fourth Proportional to 421.69, 632.55 and 387.86

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Solution

The fourth proportional to 421.69, 632.55 and 387.86 is: 581.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.69 : 632.55 = 387.86 : x
  2. Step 2: Convert to fraction form
    421.69/632.55 = 387.86/x
  3. Step 3: Cross multiply
    421.69x = 632.55 × 387.86
  4. Step 4: Simplify right side
    421.69x = 245,340.84
  5. Step 5: Solve for x
    x = 245,340.84/421.69
  6. Step 6: Final answer
    x = 581.80

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.