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Finding the Fourth Proportional to 209.13, 311.99 and 206.40

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Solution

The fourth proportional to 209.13, 311.99 and 206.40 is: 307.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.13 : 311.99 = 206.40 : x
  2. Step 2: Convert to fraction form
    209.13/311.99 = 206.40/x
  3. Step 3: Cross multiply
    209.13x = 311.99 × 206.40
  4. Step 4: Simplify right side
    209.13x = 64,393.99
  5. Step 5: Solve for x
    x = 64,393.99/209.13
  6. Step 6: Final answer
    x = 307.91

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.