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Finding the Fourth Proportional to 105, 145.14 and 81.70

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Solution

The fourth proportional to 105, 145.14 and 81.70 is: 112.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    105 : 145.14 = 81.70 : x
  2. Step 2: Convert to fraction form
    105/145.14 = 81.70/x
  3. Step 3: Cross multiply
    105x = 145.14 × 81.70
  4. Step 4: Simplify right side
    105x = 11,857.94
  5. Step 5: Solve for x
    x = 11,857.94/105
  6. Step 6: Final answer
    x = 112.93

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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.