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Finding the Fourth Proportional to 139.68, 209.58 and 71.22

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Solution

The fourth proportional to 139.68, 209.58 and 71.22 is: 106.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.68 : 209.58 = 71.22 : x
  2. Step 2: Convert to fraction form
    139.68/209.58 = 71.22/x
  3. Step 3: Cross multiply
    139.68x = 209.58 × 71.22
  4. Step 4: Simplify right side
    139.68x = 14,925.93
  5. Step 5: Solve for x
    x = 14,925.93/139.68
  6. Step 6: Final answer
    x = 106.86

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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.