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Finding the Fourth Proportional to 172.58, 258.79 and 69.78

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Solution

The fourth proportional to 172.58, 258.79 and 69.78 is: 104.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.58 : 258.79 = 69.78 : x
  2. Step 2: Convert to fraction form
    172.58/258.79 = 69.78/x
  3. Step 3: Cross multiply
    172.58x = 258.79 × 69.78
  4. Step 4: Simplify right side
    172.58x = 18,058.37
  5. Step 5: Solve for x
    x = 18,058.37/172.58
  6. Step 6: Final answer
    x = 104.64

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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.