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Finding the Fourth Proportional to 139.78, 192.92 and 90.66

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Solution

The fourth proportional to 139.78, 192.92 and 90.66 is: 125.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.78 : 192.92 = 90.66 : x
  2. Step 2: Convert to fraction form
    139.78/192.92 = 90.66/x
  3. Step 3: Cross multiply
    139.78x = 192.92 × 90.66
  4. Step 4: Simplify right side
    139.78x = 17,490.13
  5. Step 5: Solve for x
    x = 17,490.13/139.78
  6. Step 6: Final answer
    x = 125.13

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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.