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Finding the Fourth Proportional to 136.80, 188.78 and 78.57

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Solution

The fourth proportional to 136.80, 188.78 and 78.57 is: 108.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.80 : 188.78 = 78.57 : x
  2. Step 2: Convert to fraction form
    136.80/188.78 = 78.57/x
  3. Step 3: Cross multiply
    136.80x = 188.78 × 78.57
  4. Step 4: Simplify right side
    136.80x = 14,832.05
  5. Step 5: Solve for x
    x = 14,832.05/136.80
  6. Step 6: Final answer
    x = 108.42

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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.