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Finding the Fourth Proportional to 67.20, 100.80 and 45.78

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Solution

The fourth proportional to 67.20, 100.80 and 45.78 is: 68.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    67.20 : 100.80 = 45.78 : x
  2. Step 2: Convert to fraction form
    67.20/100.80 = 45.78/x
  3. Step 3: Cross multiply
    67.20x = 100.80 × 45.78
  4. Step 4: Simplify right side
    67.20x = 4,614.62
  5. Step 5: Solve for x
    x = 4,614.62/67.20
  6. Step 6: Final answer
    x = 68.67

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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.