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Finding the Fourth Proportional to 206.45, 309.76 and 90.89

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Solution

The fourth proportional to 206.45, 309.76 and 90.89 is: 136.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.45 : 309.76 = 90.89 : x
  2. Step 2: Convert to fraction form
    206.45/309.76 = 90.89/x
  3. Step 3: Cross multiply
    206.45x = 309.76 × 90.89
  4. Step 4: Simplify right side
    206.45x = 28,152.31
  5. Step 5: Solve for x
    x = 28,152.31/206.45
  6. Step 6: Final answer
    x = 136.36

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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.