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Finding the Fourth Proportional to 689.38, 1,033.80 and 278.40

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Solution

The fourth proportional to 689.38, 1,033.80 and 278.40 is: 417.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.38 : 1,033.80 = 278.40 : x
  2. Step 2: Convert to fraction form
    689.38/1,033.80 = 278.40/x
  3. Step 3: Cross multiply
    689.38x = 1,033.80 × 278.40
  4. Step 4: Simplify right side
    689.38x = 287,809.92
  5. Step 5: Solve for x
    x = 287,809.92/689.38
  6. Step 6: Final answer
    x = 417.49

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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.