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Finding the Fourth Proportional to 189.90, 284.99 and 81.72

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Solution

The fourth proportional to 189.90, 284.99 and 81.72 is: 122.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    189.90 : 284.99 = 81.72 : x
  2. Step 2: Convert to fraction form
    189.90/284.99 = 81.72/x
  3. Step 3: Cross multiply
    189.90x = 284.99 × 81.72
  4. Step 4: Simplify right side
    189.90x = 23,288.97
  5. Step 5: Solve for x
    x = 23,288.97/189.90
  6. Step 6: Final answer
    x = 122.64

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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.