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Finding the Fourth Proportional to 128.79, 193.19 and 47.66

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Solution

The fourth proportional to 128.79, 193.19 and 47.66 is: 71.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.79 : 193.19 = 47.66 : x
  2. Step 2: Convert to fraction form
    128.79/193.19 = 47.66/x
  3. Step 3: Cross multiply
    128.79x = 193.19 × 47.66
  4. Step 4: Simplify right side
    128.79x = 9,206.23
  5. Step 5: Solve for x
    x = 9,206.23/128.79
  6. Step 6: Final answer
    x = 71.48

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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.