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Finding the Fourth Proportional to 920.78, 1,269.19 and 721.27

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Solution

The fourth proportional to 920.78, 1,269.19 and 721.27 is: 994.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.78 : 1,269.19 = 721.27 : x
  2. Step 2: Convert to fraction form
    920.78/1,269.19 = 721.27/x
  3. Step 3: Cross multiply
    920.78x = 1,269.19 × 721.27
  4. Step 4: Simplify right side
    920.78x = 915,428.67
  5. Step 5: Solve for x
    x = 915,428.67/920.78
  6. Step 6: Final answer
    x = 994.19

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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.