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Finding the Fourth Proportional to 207.95, 311.90 and 86.15

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Solution

The fourth proportional to 207.95, 311.90 and 86.15 is: 129.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.95 : 311.90 = 86.15 : x
  2. Step 2: Convert to fraction form
    207.95/311.90 = 86.15/x
  3. Step 3: Cross multiply
    207.95x = 311.90 × 86.15
  4. Step 4: Simplify right side
    207.95x = 26,868.19
  5. Step 5: Solve for x
    x = 26,868.19/207.95
  6. Step 6: Final answer
    x = 129.21

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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.