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Finding the Fourth Proportional to 1,287.08, 1,930.98 and 421.64

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Solution

The fourth proportional to 1,287.08, 1,930.98 and 421.64 is: 632.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.08 : 1,930.98 = 421.64 : x
  2. Step 2: Convert to fraction form
    1,287.08/1,930.98 = 421.64/x
  3. Step 3: Cross multiply
    1,287.08x = 1,930.98 × 421.64
  4. Step 4: Simplify right side
    1,287.08x = 814,178.41
  5. Step 5: Solve for x
    x = 814,178.41/1,287.08
  6. Step 6: Final answer
    x = 632.58

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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.