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Finding the Fourth Proportional to 128.51, 192.66 and 85.11

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Solution

The fourth proportional to 128.51, 192.66 and 85.11 is: 127.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.51 : 192.66 = 85.11 : x
  2. Step 2: Convert to fraction form
    128.51/192.66 = 85.11/x
  3. Step 3: Cross multiply
    128.51x = 192.66 × 85.11
  4. Step 4: Simplify right side
    128.51x = 16,397.29
  5. Step 5: Solve for x
    x = 16,397.29/128.51
  6. Step 6: Final answer
    x = 127.60

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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.