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Finding the Fourth Proportional to 1,287.52, 1,932 and 638.88

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Solution

The fourth proportional to 1,287.52, 1,932 and 638.88 is: 958.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.52 : 1,932 = 638.88 : x
  2. Step 2: Convert to fraction form
    1,287.52/1,932 = 638.88/x
  3. Step 3: Cross multiply
    1,287.52x = 1,932 × 638.88
  4. Step 4: Simplify right side
    1,287.52x = 1,234,316.16
  5. Step 5: Solve for x
    x = 1,234,316.16/1,287.52
  6. Step 6: Final answer
    x = 958.68

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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.