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Finding the Fourth Proportional to 427.40, 639.90 and 384.20

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Solution

The fourth proportional to 427.40, 639.90 and 384.20 is: 575.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.40 : 639.90 = 384.20 : x
  2. Step 2: Convert to fraction form
    427.40/639.90 = 384.20/x
  3. Step 3: Cross multiply
    427.40x = 639.90 × 384.20
  4. Step 4: Simplify right side
    427.40x = 245,849.58
  5. Step 5: Solve for x
    x = 245,849.58/427.40
  6. Step 6: Final answer
    x = 575.22

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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.