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Finding the Fourth Proportional to 989.13, 1,365.13 and 639.75

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Solution

The fourth proportional to 989.13, 1,365.13 and 639.75 is: 882.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.13 : 1,365.13 = 639.75 : x
  2. Step 2: Convert to fraction form
    989.13/1,365.13 = 639.75/x
  3. Step 3: Cross multiply
    989.13x = 1,365.13 × 639.75
  4. Step 4: Simplify right side
    989.13x = 873,341.92
  5. Step 5: Solve for x
    x = 873,341.92/989.13
  6. Step 6: Final answer
    x = 882.94

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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.