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Finding the Fourth Proportional to 128.58, 192.86 and 79.84

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Solution

The fourth proportional to 128.58, 192.86 and 79.84 is: 119.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.58 : 192.86 = 79.84 : x
  2. Step 2: Convert to fraction form
    128.58/192.86 = 79.84/x
  3. Step 3: Cross multiply
    128.58x = 192.86 × 79.84
  4. Step 4: Simplify right side
    128.58x = 15,397.94
  5. Step 5: Solve for x
    x = 15,397.94/128.58
  6. Step 6: Final answer
    x = 119.75

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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.