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Finding the Fourth Proportional to 429.30, 643.87 and 121.18

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Solution

The fourth proportional to 429.30, 643.87 and 121.18 is: 181.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.30 : 643.87 = 121.18 : x
  2. Step 2: Convert to fraction form
    429.30/643.87 = 121.18/x
  3. Step 3: Cross multiply
    429.30x = 643.87 × 121.18
  4. Step 4: Simplify right side
    429.30x = 78,024.17
  5. Step 5: Solve for x
    x = 78,024.17/429.30
  6. Step 6: Final answer
    x = 181.75

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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.