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Finding the Fourth Proportional to 139.63, 210.56 and 138.72

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Solution

The fourth proportional to 139.63, 210.56 and 138.72 is: 209.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.63 : 210.56 = 138.72 : x
  2. Step 2: Convert to fraction form
    139.63/210.56 = 138.72/x
  3. Step 3: Cross multiply
    139.63x = 210.56 × 138.72
  4. Step 4: Simplify right side
    139.63x = 29,208.37
  5. Step 5: Solve for x
    x = 29,208.37/139.63
  6. Step 6: Final answer
    x = 209.19

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.