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Finding the Fourth Proportional to 139.94, 209.95 and 71.40

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Solution

The fourth proportional to 139.94, 209.95 and 71.40 is: 107.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.94 : 209.95 = 71.40 : x
  2. Step 2: Convert to fraction form
    139.94/209.95 = 71.40/x
  3. Step 3: Cross multiply
    139.94x = 209.95 × 71.40
  4. Step 4: Simplify right side
    139.94x = 14,990.43
  5. Step 5: Solve for x
    x = 14,990.43/139.94
  6. Step 6: Final answer
    x = 107.12

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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.