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Finding the Fourth Proportional to 920, 1,269.72 and 640.08

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Solution

The fourth proportional to 920, 1,269.72 and 640.08 is: 883.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    920 : 1,269.72 = 640.08 : x
  2. Step 2: Convert to fraction form
    920/1,269.72 = 640.08/x
  3. Step 3: Cross multiply
    920x = 1,269.72 × 640.08
  4. Step 4: Simplify right side
    920x = 812,722.38
  5. Step 5: Solve for x
    x = 812,722.38/920
  6. Step 6: Final answer
    x = 883.39

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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.