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Finding the Fourth Proportional to 138.90, 191.70 and 92.31

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Solution

The fourth proportional to 138.90, 191.70 and 92.31 is: 127.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.90 : 191.70 = 92.31 : x
  2. Step 2: Convert to fraction form
    138.90/191.70 = 92.31/x
  3. Step 3: Cross multiply
    138.90x = 191.70 × 92.31
  4. Step 4: Simplify right side
    138.90x = 17,695.83
  5. Step 5: Solve for x
    x = 17,695.83/138.90
  6. Step 6: Final answer
    x = 127.40

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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.