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Finding the Fourth Proportional to 420.72, 579.72 and 393.12

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Solution

The fourth proportional to 420.72, 579.72 and 393.12 is: 541.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.72 : 579.72 = 393.12 : x
  2. Step 2: Convert to fraction form
    420.72/579.72 = 393.12/x
  3. Step 3: Cross multiply
    420.72x = 579.72 × 393.12
  4. Step 4: Simplify right side
    420.72x = 227,899.53
  5. Step 5: Solve for x
    x = 227,899.53/420.72
  6. Step 6: Final answer
    x = 541.69

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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.