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Finding the Fourth Proportional to 1,320.66, 1,980.40 and 396.05

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Solution

The fourth proportional to 1,320.66, 1,980.40 and 396.05 is: 593.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.66 : 1,980.40 = 396.05 : x
  2. Step 2: Convert to fraction form
    1,320.66/1,980.40 = 396.05/x
  3. Step 3: Cross multiply
    1,320.66x = 1,980.40 × 396.05
  4. Step 4: Simplify right side
    1,320.66x = 784,327.52
  5. Step 5: Solve for x
    x = 784,327.52/1,320.66
  6. Step 6: Final answer
    x = 593.89

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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.