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Finding the Fourth Proportional to 128.59, 192.81 and 79.72

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Solution

The fourth proportional to 128.59, 192.81 and 79.72 is: 119.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.59 : 192.81 = 79.72 : x
  2. Step 2: Convert to fraction form
    128.59/192.81 = 79.72/x
  3. Step 3: Cross multiply
    128.59x = 192.81 × 79.72
  4. Step 4: Simplify right side
    128.59x = 15,370.63
  5. Step 5: Solve for x
    x = 15,370.63/128.59
  6. Step 6: Final answer
    x = 119.53

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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.