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Finding the Fourth Proportional to 145.12, 217.76 and 81.12

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Solution

The fourth proportional to 145.12, 217.76 and 81.12 is: 121.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    145.12 : 217.76 = 81.12 : x
  2. Step 2: Convert to fraction form
    145.12/217.76 = 81.12/x
  3. Step 3: Cross multiply
    145.12x = 217.76 × 81.12
  4. Step 4: Simplify right side
    145.12x = 17,664.69
  5. Step 5: Solve for x
    x = 17,664.69/145.12
  6. Step 6: Final answer
    x = 121.72

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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.