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Finding the Fourth Proportional to 930.78, 1,396.42 and 520.21

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Solution

The fourth proportional to 930.78, 1,396.42 and 520.21 is: 780.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    930.78 : 1,396.42 = 520.21 : x
  2. Step 2: Convert to fraction form
    930.78/1,396.42 = 520.21/x
  3. Step 3: Cross multiply
    930.78x = 1,396.42 × 520.21
  4. Step 4: Simplify right side
    930.78x = 726,426.86
  5. Step 5: Solve for x
    x = 726,426.86/930.78
  6. Step 6: Final answer
    x = 780.45

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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.