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Finding the Fourth Proportional to 427.20, 639.59 and 319.47

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Solution

The fourth proportional to 427.20, 639.59 and 319.47 is: 478.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.20 : 639.59 = 319.47 : x
  2. Step 2: Convert to fraction form
    427.20/639.59 = 319.47/x
  3. Step 3: Cross multiply
    427.20x = 639.59 × 319.47
  4. Step 4: Simplify right side
    427.20x = 204,328.22
  5. Step 5: Solve for x
    x = 204,328.22/427.20
  6. Step 6: Final answer
    x = 478.30

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.