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Finding the Fourth Proportional to 987.96, 1,362.81 and 638.65

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Solution

The fourth proportional to 987.96, 1,362.81 and 638.65 is: 880.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.96 : 1,362.81 = 638.65 : x
  2. Step 2: Convert to fraction form
    987.96/1,362.81 = 638.65/x
  3. Step 3: Cross multiply
    987.96x = 1,362.81 × 638.65
  4. Step 4: Simplify right side
    987.96x = 870,358.61
  5. Step 5: Solve for x
    x = 870,358.61/987.96
  6. Step 6: Final answer
    x = 880.97

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.