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Finding the Fourth Proportional to 429, 643.52 and 120.85

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Solution

The fourth proportional to 429, 643.52 and 120.85 is: 181.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    429 : 643.52 = 120.85 : x
  2. Step 2: Convert to fraction form
    429/643.52 = 120.85/x
  3. Step 3: Cross multiply
    429x = 643.52 × 120.85
  4. Step 4: Simplify right side
    429x = 77,769.39
  5. Step 5: Solve for x
    x = 77,769.39/429
  6. Step 6: Final answer
    x = 181.28

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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.