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Finding the Fourth Proportional to 139.76, 209.72 and 91.60

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Solution

The fourth proportional to 139.76, 209.72 and 91.60 is: 137.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.76 : 209.72 = 91.60 : x
  2. Step 2: Convert to fraction form
    139.76/209.72 = 91.60/x
  3. Step 3: Cross multiply
    139.76x = 209.72 × 91.60
  4. Step 4: Simplify right side
    139.76x = 19,210.35
  5. Step 5: Solve for x
    x = 19,210.35/139.76
  6. Step 6: Final answer
    x = 137.45

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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.