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Finding the Fourth Proportional to 124.65, 171.90 and 81

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Solution

The fourth proportional to 124.65, 171.90 and 81 is: 111.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    124.65 : 171.90 = 81 : x
  2. Step 2: Convert to fraction form
    124.65/171.90 = 81/x
  3. Step 3: Cross multiply
    124.65x = 171.90 × 81
  4. Step 4: Simplify right side
    124.65x = 13,923.90
  5. Step 5: Solve for x
    x = 13,923.90/124.65
  6. Step 6: Final answer
    x = 111.70

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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.