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Finding the Fourth Proportional to 128.49, 192.60 and 79.74

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Solution

The fourth proportional to 128.49, 192.60 and 79.74 is: 119.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.49 : 192.60 = 79.74 : x
  2. Step 2: Convert to fraction form
    128.49/192.60 = 79.74/x
  3. Step 3: Cross multiply
    128.49x = 192.60 × 79.74
  4. Step 4: Simplify right side
    128.49x = 15,357.92
  5. Step 5: Solve for x
    x = 15,357.92/128.49
  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.