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Finding the Fourth Proportional to 105.71, 145.61 and 81.11

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Solution

The fourth proportional to 105.71, 145.61 and 81.11 is: 111.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.71 : 145.61 = 81.11 : x
  2. Step 2: Convert to fraction form
    105.71/145.61 = 81.11/x
  3. Step 3: Cross multiply
    105.71x = 145.61 × 81.11
  4. Step 4: Simplify right side
    105.71x = 11,809.60
  5. Step 5: Solve for x
    x = 11,809.60/105.71
  6. Step 6: Final answer
    x = 111.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.