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Finding the Fourth Proportional to 172.14, 258.40 and 138.30

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Solution

The fourth proportional to 172.14, 258.40 and 138.30 is: 207.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.14 : 258.40 = 138.30 : x
  2. Step 2: Convert to fraction form
    172.14/258.40 = 138.30/x
  3. Step 3: Cross multiply
    172.14x = 258.40 × 138.30
  4. Step 4: Simplify right side
    172.14x = 35,736.72
  5. Step 5: Solve for x
    x = 35,736.72/172.14
  6. Step 6: Final answer
    x = 207.60

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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.