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Finding the Fourth Proportional to 428.89, 643.33 and 120.74

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Solution

The fourth proportional to 428.89, 643.33 and 120.74 is: 181.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.89 : 643.33 = 120.74 : x
  2. Step 2: Convert to fraction form
    428.89/643.33 = 120.74/x
  3. Step 3: Cross multiply
    428.89x = 643.33 × 120.74
  4. Step 4: Simplify right side
    428.89x = 77,675.66
  5. Step 5: Solve for x
    x = 77,675.66/428.89
  6. Step 6: Final answer
    x = 181.11

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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.