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Finding the Fourth Proportional to 420.30, 579.30 and 321.90

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Solution

The fourth proportional to 420.30, 579.30 and 321.90 is: 443.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.30 : 579.30 = 321.90 : x
  2. Step 2: Convert to fraction form
    420.30/579.30 = 321.90/x
  3. Step 3: Cross multiply
    420.30x = 579.30 × 321.90
  4. Step 4: Simplify right side
    420.30x = 186,476.67
  5. Step 5: Solve for x
    x = 186,476.67/420.30
  6. Step 6: Final answer
    x = 443.68

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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.