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Finding the Fourth Proportional to 428.79, 642.78 and 185.49

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Solution

The fourth proportional to 428.79, 642.78 and 185.49 is: 278.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.79 : 642.78 = 185.49 : x
  2. Step 2: Convert to fraction form
    428.79/642.78 = 185.49/x
  3. Step 3: Cross multiply
    428.79x = 642.78 × 185.49
  4. Step 4: Simplify right side
    428.79x = 119,229.26
  5. Step 5: Solve for x
    x = 119,229.26/428.79
  6. Step 6: Final answer
    x = 278.06

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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.