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Finding the Fourth Proportional to 987.69, 1,363.03 and 638.99

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Solution

The fourth proportional to 987.69, 1,363.03 and 638.99 is: 881.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.69 : 1,363.03 = 638.99 : x
  2. Step 2: Convert to fraction form
    987.69/1,363.03 = 638.99/x
  3. Step 3: Cross multiply
    987.69x = 1,363.03 × 638.99
  4. Step 4: Simplify right side
    987.69x = 870,952.53
  5. Step 5: Solve for x
    x = 870,952.53/987.69
  6. Step 6: Final answer
    x = 881.81

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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.