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Finding the Fourth Proportional to 207.90, 311.90 and 86.10

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Solution

The fourth proportional to 207.90, 311.90 and 86.10 is: 129.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.90 : 311.90 = 86.10 : x
  2. Step 2: Convert to fraction form
    207.90/311.90 = 86.10/x
  3. Step 3: Cross multiply
    207.90x = 311.90 × 86.10
  4. Step 4: Simplify right side
    207.90x = 26,852.99
  5. Step 5: Solve for x
    x = 26,852.99/207.90
  6. Step 6: Final answer
    x = 129.16

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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.