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Finding the Fourth Proportional to 989.78, 1,365.92 and 547.72

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Solution

The fourth proportional to 989.78, 1,365.92 and 547.72 is: 755.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.78 : 1,365.92 = 547.72 : x
  2. Step 2: Convert to fraction form
    989.78/1,365.92 = 547.72/x
  3. Step 3: Cross multiply
    989.78x = 1,365.92 × 547.72
  4. Step 4: Simplify right side
    989.78x = 748,139.66
  5. Step 5: Solve for x
    x = 748,139.66/989.78
  6. Step 6: Final answer
    x = 755.87

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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.