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Finding the Fourth Proportional to 638.40, 957.36 and 421.68

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Solution

The fourth proportional to 638.40, 957.36 and 421.68 is: 632.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.40 : 957.36 = 421.68 : x
  2. Step 2: Convert to fraction form
    638.40/957.36 = 421.68/x
  3. Step 3: Cross multiply
    638.40x = 957.36 × 421.68
  4. Step 4: Simplify right side
    638.40x = 403,699.56
  5. Step 5: Solve for x
    x = 403,699.56/638.40
  6. Step 6: Final answer
    x = 632.36

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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.