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Finding the Fourth Proportional to 128.42, 192.39 and 79.60

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Solution

The fourth proportional to 128.42, 192.39 and 79.60 is: 119.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.42 : 192.39 = 79.60 : x
  2. Step 2: Convert to fraction form
    128.42/192.39 = 79.60/x
  3. Step 3: Cross multiply
    128.42x = 192.39 × 79.60
  4. Step 4: Simplify right side
    128.42x = 15,314.24
  5. Step 5: Solve for x
    x = 15,314.24/128.42
  6. Step 6: Final answer
    x = 119.25

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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.