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Finding the Fourth Proportional to 128.68, 193 and 66.98

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Solution

The fourth proportional to 128.68, 193 and 66.98 is: 100.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.68 : 193 = 66.98 : x
  2. Step 2: Convert to fraction form
    128.68/193 = 66.98/x
  3. Step 3: Cross multiply
    128.68x = 193 × 66.98
  4. Step 4: Simplify right side
    128.68x = 12,926.18
  5. Step 5: Solve for x
    x = 12,926.18/128.68
  6. Step 6: Final answer
    x = 100.45

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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.