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Finding the Fourth Proportional to 172.90, 259 and 81.68

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Solution

The fourth proportional to 172.90, 259 and 81.68 is: 122.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.90 : 259 = 81.68 : x
  2. Step 2: Convert to fraction form
    172.90/259 = 81.68/x
  3. Step 3: Cross multiply
    172.90x = 259 × 81.68
  4. Step 4: Simplify right side
    172.90x = 21,155.12
  5. Step 5: Solve for x
    x = 21,155.12/172.90
  6. Step 6: Final answer
    x = 122.35

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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.