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Finding the Fourth Proportional to 205.80, 308.62 and 128.65

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Solution

The fourth proportional to 205.80, 308.62 and 128.65 is: 192.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.80 : 308.62 = 128.65 : x
  2. Step 2: Convert to fraction form
    205.80/308.62 = 128.65/x
  3. Step 3: Cross multiply
    205.80x = 308.62 × 128.65
  4. Step 4: Simplify right side
    205.80x = 39,703.96
  5. Step 5: Solve for x
    x = 39,703.96/205.80
  6. Step 6: Final answer
    x = 192.92

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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.