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Finding the Fourth Proportional to 31.03, 42.80 and 20.67

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Solution

The fourth proportional to 31.03, 42.80 and 20.67 is: 28.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.03 : 42.80 = 20.67 : x
  2. Step 2: Convert to fraction form
    31.03/42.80 = 20.67/x
  3. Step 3: Cross multiply
    31.03x = 42.80 × 20.67
  4. Step 4: Simplify right side
    31.03x = 884.57
  5. Step 5: Solve for x
    x = 884.57/31.03
  6. Step 6: Final answer
    x = 28.50

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.