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Finding the Fourth Proportional to 420, 579.20 and 386.90

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Solution

The fourth proportional to 420, 579.20 and 386.90 is: 533.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    420 : 579.20 = 386.90 : x
  2. Step 2: Convert to fraction form
    420/579.20 = 386.90/x
  3. Step 3: Cross multiply
    420x = 579.20 × 386.90
  4. Step 4: Simplify right side
    420x = 224,087.65
  5. Step 5: Solve for x
    x = 224,087.65/420
  6. Step 6: Final answer
    x = 533.54

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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.