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Finding the Fourth Proportional to 207.70, 311 and 139.30

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Solution

The fourth proportional to 207.70, 311 and 139.30 is: 208.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.70 : 311 = 139.30 : x
  2. Step 2: Convert to fraction form
    207.70/311 = 139.30/x
  3. Step 3: Cross multiply
    207.70x = 311 × 139.30
  4. Step 4: Simplify right side
    207.70x = 43,322.30
  5. Step 5: Solve for x
    x = 43,322.30/207.70
  6. Step 6: Final answer
    x = 208.58

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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.