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Finding the Fourth Proportional to 205.68, 308.40 and 128.76

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Solution

The fourth proportional to 205.68, 308.40 and 128.76 is: 193.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.68 : 308.40 = 128.76 : x
  2. Step 2: Convert to fraction form
    205.68/308.40 = 128.76/x
  3. Step 3: Cross multiply
    205.68x = 308.40 × 128.76
  4. Step 4: Simplify right side
    205.68x = 39,709.58
  5. Step 5: Solve for x
    x = 39,709.58/205.68
  6. Step 6: Final answer
    x = 193.06

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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.