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Finding the Fourth Proportional to 128.48, 191.60 and 121.29

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Solution

The fourth proportional to 128.48, 191.60 and 121.29 is: 180.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.48 : 191.60 = 121.29 : x
  2. Step 2: Convert to fraction form
    128.48/191.60 = 121.29/x
  3. Step 3: Cross multiply
    128.48x = 191.60 × 121.29
  4. Step 4: Simplify right side
    128.48x = 23,239.16
  5. Step 5: Solve for x
    x = 23,239.16/128.48
  6. Step 6: Final answer
    x = 180.88

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.