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Finding the Fourth Proportional to 142.75, 214.20 and 85.75

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Solution

The fourth proportional to 142.75, 214.20 and 85.75 is: 128.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.75 : 214.20 = 85.75 : x
  2. Step 2: Convert to fraction form
    142.75/214.20 = 85.75/x
  3. Step 3: Cross multiply
    142.75x = 214.20 × 85.75
  4. Step 4: Simplify right side
    142.75x = 18,367.65
  5. Step 5: Solve for x
    x = 18,367.65/142.75
  6. Step 6: Final answer
    x = 128.67

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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.