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Finding the Fourth Proportional to 205.58, 308.78 and 128.59

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Solution

The fourth proportional to 205.58, 308.78 and 128.59 is: 193.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.58 : 308.78 = 128.59 : x
  2. Step 2: Convert to fraction form
    205.58/308.78 = 128.59/x
  3. Step 3: Cross multiply
    205.58x = 308.78 × 128.59
  4. Step 4: Simplify right side
    205.58x = 39,706.02
  5. Step 5: Solve for x
    x = 39,706.02/205.58
  6. Step 6: Final answer
    x = 193.14

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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.