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Finding the Fourth Proportional to 128.71, 192.99 and 67.89

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Solution

The fourth proportional to 128.71, 192.99 and 67.89 is: 101.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.71 : 192.99 = 67.89 : x
  2. Step 2: Convert to fraction form
    128.71/192.99 = 67.89/x
  3. Step 3: Cross multiply
    128.71x = 192.99 × 67.89
  4. Step 4: Simplify right side
    128.71x = 13,102.09
  5. Step 5: Solve for x
    x = 13,102.09/128.71
  6. Step 6: Final answer
    x = 101.80

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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.