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Finding the Fourth Proportional to 139.82, 208.80 and 128.30

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Solution

The fourth proportional to 139.82, 208.80 and 128.30 is: 191.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.82 : 208.80 = 128.30 : x
  2. Step 2: Convert to fraction form
    139.82/208.80 = 128.30/x
  3. Step 3: Cross multiply
    139.82x = 208.80 × 128.30
  4. Step 4: Simplify right side
    139.82x = 26,788.00
  5. Step 5: Solve for x
    x = 26,788.00/139.82
  6. Step 6: Final answer
    x = 191.60

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.