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Finding the Fourth Proportional to 420.78, 579.60 and 315.54

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Solution

The fourth proportional to 420.78, 579.60 and 315.54 is: 434.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.78 : 579.60 = 315.54 : x
  2. Step 2: Convert to fraction form
    420.78/579.60 = 315.54/x
  3. Step 3: Cross multiply
    420.78x = 579.60 × 315.54
  4. Step 4: Simplify right side
    420.78x = 182,886.98
  5. Step 5: Solve for x
    x = 182,886.98/420.78
  6. Step 6: Final answer
    x = 434.64

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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.