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Finding the Fourth Proportional to 689.60, 1,036.46 and 638.69

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Solution

The fourth proportional to 689.60, 1,036.46 and 638.69 is: 959.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.60 : 1,036.46 = 638.69 : x
  2. Step 2: Convert to fraction form
    689.60/1,036.46 = 638.69/x
  3. Step 3: Cross multiply
    689.60x = 1,036.46 × 638.69
  4. Step 4: Simplify right side
    689.60x = 661,976.64
  5. Step 5: Solve for x
    x = 661,976.64/689.60
  6. Step 6: Final answer
    x = 959.94

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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.