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Finding the Fourth Proportional to 1,321.20, 1,981.92 and 396.65

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Solution

The fourth proportional to 1,321.20, 1,981.92 and 396.65 is: 595.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.20 : 1,981.92 = 396.65 : x
  2. Step 2: Convert to fraction form
    1,321.20/1,981.92 = 396.65/x
  3. Step 3: Cross multiply
    1,321.20x = 1,981.92 × 396.65
  4. Step 4: Simplify right side
    1,321.20x = 786,118.66
  5. Step 5: Solve for x
    x = 786,118.66/1,321.20
  6. Step 6: Final answer
    x = 595.00

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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.