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Finding the Fourth Proportional to 139.47, 209.21 and 66.38

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Solution

The fourth proportional to 139.47, 209.21 and 66.38 is: 99.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.47 : 209.21 = 66.38 : x
  2. Step 2: Convert to fraction form
    139.47/209.21 = 66.38/x
  3. Step 3: Cross multiply
    139.47x = 209.21 × 66.38
  4. Step 4: Simplify right side
    139.47x = 13,888.05
  5. Step 5: Solve for x
    x = 13,888.05/139.47
  6. Step 6: Final answer
    x = 99.58

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.