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Finding the Fourth Proportional to 138.63, 191.31 and 128.32

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Solution

The fourth proportional to 138.63, 191.31 and 128.32 is: 177.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.63 : 191.31 = 128.32 : x
  2. Step 2: Convert to fraction form
    138.63/191.31 = 128.32/x
  3. Step 3: Cross multiply
    138.63x = 191.31 × 128.32
  4. Step 4: Simplify right side
    138.63x = 24,548.90
  5. Step 5: Solve for x
    x = 24,548.90/138.63
  6. Step 6: Final answer
    x = 177.08

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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.