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Finding the Fourth Proportional to 189.78, 261.80 and 112.15

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Solution

The fourth proportional to 189.78, 261.80 and 112.15 is: 154.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    189.78 : 261.80 = 112.15 : x
  2. Step 2: Convert to fraction form
    189.78/261.80 = 112.15/x
  3. Step 3: Cross multiply
    189.78x = 261.80 × 112.15
  4. Step 4: Simplify right side
    189.78x = 29,360.31
  5. Step 5: Solve for x
    x = 29,360.31/189.78
  6. Step 6: Final answer
    x = 154.71

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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.