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Finding the Fourth Proportional to 428.90, 643.75 and 185.69

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Solution

The fourth proportional to 428.90, 643.75 and 185.69 is: 278.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.90 : 643.75 = 185.69 : x
  2. Step 2: Convert to fraction form
    428.90/643.75 = 185.69/x
  3. Step 3: Cross multiply
    428.90x = 643.75 × 185.69
  4. Step 4: Simplify right side
    428.90x = 119,539.08
  5. Step 5: Solve for x
    x = 119,539.08/428.90
  6. Step 6: Final answer
    x = 278.71

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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.