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Finding the Fourth Proportional to 129.78, 195.66 and 128.16

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Solution

The fourth proportional to 129.78, 195.66 and 128.16 is: 193.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.78 : 195.66 = 128.16 : x
  2. Step 2: Convert to fraction form
    129.78/195.66 = 128.16/x
  3. Step 3: Cross multiply
    129.78x = 195.66 × 128.16
  4. Step 4: Simplify right side
    129.78x = 25,075.79
  5. Step 5: Solve for x
    x = 25,075.79/129.78
  6. Step 6: Final answer
    x = 193.22

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.