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Finding the Fourth Proportional to 425.43, 642.80 and 423

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Solution

The fourth proportional to 425.43, 642.80 and 423 is: 639.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    425.43 : 642.80 = 423 : x
  2. Step 2: Convert to fraction form
    425.43/642.80 = 423/x
  3. Step 3: Cross multiply
    425.43x = 642.80 × 423
  4. Step 4: Simplify right side
    425.43x = 271,905.46
  5. Step 5: Solve for x
    x = 271,905.46/425.43
  6. Step 6: Final answer
    x = 639.13

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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.