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Finding the Fourth Proportional to 172.78, 238.47 and 99.09

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Solution

The fourth proportional to 172.78, 238.47 and 99.09 is: 136.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.78 : 238.47 = 99.09 : x
  2. Step 2: Convert to fraction form
    172.78/238.47 = 99.09/x
  3. Step 3: Cross multiply
    172.78x = 238.47 × 99.09
  4. Step 4: Simplify right side
    172.78x = 23,628.80
  5. Step 5: Solve for x
    x = 23,628.80/172.78
  6. Step 6: Final answer
    x = 136.75

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.