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Finding the Fourth Proportional to 135.78, 187.38 and 84

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Solution

The fourth proportional to 135.78, 187.38 and 84 is: 115.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    135.78 : 187.38 = 84 : x
  2. Step 2: Convert to fraction form
    135.78/187.38 = 84/x
  3. Step 3: Cross multiply
    135.78x = 187.38 × 84
  4. Step 4: Simplify right side
    135.78x = 15,739.92
  5. Step 5: Solve for x
    x = 15,739.92/135.78
  6. Step 6: Final answer
    x = 115.92

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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.