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Finding the Fourth Proportional to 428.97, 643.49 and 120.82

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Solution

The fourth proportional to 428.97, 643.49 and 120.82 is: 181.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.97 : 643.49 = 120.82 : x
  2. Step 2: Convert to fraction form
    428.97/643.49 = 120.82/x
  3. Step 3: Cross multiply
    428.97x = 643.49 × 120.82
  4. Step 4: Simplify right side
    428.97x = 77,746.46
  5. Step 5: Solve for x
    x = 77,746.46/428.97
  6. Step 6: Final answer
    x = 181.24

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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.