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Finding the Fourth Proportional to 128.42, 192.45 and 59.91

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Solution

The fourth proportional to 128.42, 192.45 and 59.91 is: 89.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.42 : 192.45 = 59.91 : x
  2. Step 2: Convert to fraction form
    128.42/192.45 = 59.91/x
  3. Step 3: Cross multiply
    128.42x = 192.45 × 59.91
  4. Step 4: Simplify right side
    128.42x = 11,529.18
  5. Step 5: Solve for x
    x = 11,529.18/128.42
  6. Step 6: Final answer
    x = 89.78

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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.