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Finding the Fourth Proportional to 172.56, 258.96 and 87.12

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Solution

The fourth proportional to 172.56, 258.96 and 87.12 is: 130.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.56 : 258.96 = 87.12 : x
  2. Step 2: Convert to fraction form
    172.56/258.96 = 87.12/x
  3. Step 3: Cross multiply
    172.56x = 258.96 × 87.12
  4. Step 4: Simplify right side
    172.56x = 22,560.60
  5. Step 5: Solve for x
    x = 22,560.60/172.56
  6. Step 6: Final answer
    x = 130.74

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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.