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Finding the Fourth Proportional to 172.50, 258.74 and 85.80

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Solution

The fourth proportional to 172.50, 258.74 and 85.80 is: 128.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.50 : 258.74 = 85.80 : x
  2. Step 2: Convert to fraction form
    172.50/258.74 = 85.80/x
  3. Step 3: Cross multiply
    172.50x = 258.74 × 85.80
  4. Step 4: Simplify right side
    172.50x = 22,200.11
  5. Step 5: Solve for x
    x = 22,200.11/172.50
  6. Step 6: Final answer
    x = 128.70

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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.