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Finding the Fourth Proportional to 206.79, 309.93 and 91.20

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Solution

The fourth proportional to 206.79, 309.93 and 91.20 is: 136.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.79 : 309.93 = 91.20 : x
  2. Step 2: Convert to fraction form
    206.79/309.93 = 91.20/x
  3. Step 3: Cross multiply
    206.79x = 309.93 × 91.20
  4. Step 4: Simplify right side
    206.79x = 28,265.62
  5. Step 5: Solve for x
    x = 28,265.62/206.79
  6. Step 6: Final answer
    x = 136.69

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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.