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Finding the Fourth Proportional to 638.40, 957.60 and 557.40

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Solution

The fourth proportional to 638.40, 957.60 and 557.40 is: 836.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.40 : 957.60 = 557.40 : x
  2. Step 2: Convert to fraction form
    638.40/957.60 = 557.40/x
  3. Step 3: Cross multiply
    638.40x = 957.60 × 557.40
  4. Step 4: Simplify right side
    638.40x = 533,766.24
  5. Step 5: Solve for x
    x = 533,766.24/638.40
  6. Step 6: Final answer
    x = 836.10

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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.