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Finding the Fourth Proportional to 428.76, 646.65 and 381.78

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Solution

The fourth proportional to 428.76, 646.65 and 381.78 is: 575.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.76 : 646.65 = 381.78 : x
  2. Step 2: Convert to fraction form
    428.76/646.65 = 381.78/x
  3. Step 3: Cross multiply
    428.76x = 646.65 × 381.78
  4. Step 4: Simplify right side
    428.76x = 246,878.04
  5. Step 5: Solve for x
    x = 246,878.04/428.76
  6. Step 6: Final answer
    x = 575.80

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.