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Finding the Fourth Proportional to 139.78, 193 and 90.70

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Solution

The fourth proportional to 139.78, 193 and 90.70 is: 125.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.78 : 193 = 90.70 : x
  2. Step 2: Convert to fraction form
    139.78/193 = 90.70/x
  3. Step 3: Cross multiply
    139.78x = 193 × 90.70
  4. Step 4: Simplify right side
    139.78x = 17,505.10
  5. Step 5: Solve for x
    x = 17,505.10/139.78
  6. Step 6: Final answer
    x = 125.23

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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.