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Finding the Fourth Proportional to 420.65, 579.96 and 287.72

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Solution

The fourth proportional to 420.65, 579.96 and 287.72 is: 396.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.65 : 579.96 = 287.72 : x
  2. Step 2: Convert to fraction form
    420.65/579.96 = 287.72/x
  3. Step 3: Cross multiply
    420.65x = 579.96 × 287.72
  4. Step 4: Simplify right side
    420.65x = 166,863.19
  5. Step 5: Solve for x
    x = 166,863.19/420.65
  6. Step 6: Final answer
    x = 396.68

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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.