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Finding the Fourth Proportional to 139.02, 208.74 and 85.25

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Solution

The fourth proportional to 139.02, 208.74 and 85.25 is: 128.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.02 : 208.74 = 85.25 : x
  2. Step 2: Convert to fraction form
    139.02/208.74 = 85.25/x
  3. Step 3: Cross multiply
    139.02x = 208.74 × 85.25
  4. Step 4: Simplify right side
    139.02x = 17,795.93
  5. Step 5: Solve for x
    x = 17,795.93/139.02
  6. Step 6: Final answer
    x = 128.01

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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.