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Finding the Fourth Proportional to 920.45, 1,269.86 and 640.91

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Solution

The fourth proportional to 920.45, 1,269.86 and 640.91 is: 884.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.45 : 1,269.86 = 640.91 : x
  2. Step 2: Convert to fraction form
    920.45/1,269.86 = 640.91/x
  3. Step 3: Cross multiply
    920.45x = 1,269.86 × 640.91
  4. Step 4: Simplify right side
    920.45x = 813,865.94
  5. Step 5: Solve for x
    x = 813,865.94/920.45
  6. Step 6: Final answer
    x = 884.20

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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.