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Finding the Fourth Proportional to 136.91, 188.94 and 78.71

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Solution

The fourth proportional to 136.91, 188.94 and 78.71 is: 108.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.91 : 188.94 = 78.71 : x
  2. Step 2: Convert to fraction form
    136.91/188.94 = 78.71/x
  3. Step 3: Cross multiply
    136.91x = 188.94 × 78.71
  4. Step 4: Simplify right side
    136.91x = 14,871.47
  5. Step 5: Solve for x
    x = 14,871.47/136.91
  6. Step 6: Final answer
    x = 108.62

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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.