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Finding the Fourth Proportional to 520.72, 779.72 and 428.40

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Solution

The fourth proportional to 520.72, 779.72 and 428.40 is: 641.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    520.72 : 779.72 = 428.40 : x
  2. Step 2: Convert to fraction form
    520.72/779.72 = 428.40/x
  3. Step 3: Cross multiply
    520.72x = 779.72 × 428.40
  4. Step 4: Simplify right side
    520.72x = 334,032.05
  5. Step 5: Solve for x
    x = 334,032.05/520.72
  6. Step 6: Final answer
    x = 641.48

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.