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Finding the Fourth Proportional to 136.80, 188.68 and 85

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Solution

The fourth proportional to 136.80, 188.68 and 85 is: 117.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.80 : 188.68 = 85 : x
  2. Step 2: Convert to fraction form
    136.80/188.68 = 85/x
  3. Step 3: Cross multiply
    136.80x = 188.68 × 85
  4. Step 4: Simplify right side
    136.80x = 16,037.80
  5. Step 5: Solve for x
    x = 16,037.80/136.80
  6. Step 6: Final answer
    x = 117.24

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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.