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Finding the Fourth Proportional to 105.72, 145.90 and 66.38

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Solution

The fourth proportional to 105.72, 145.90 and 66.38 is: 91.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.72 : 145.90 = 66.38 : x
  2. Step 2: Convert to fraction form
    105.72/145.90 = 66.38/x
  3. Step 3: Cross multiply
    105.72x = 145.90 × 66.38
  4. Step 4: Simplify right side
    105.72x = 9,685.04
  5. Step 5: Solve for x
    x = 9,685.04/105.72
  6. Step 6: Final answer
    x = 91.61

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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.