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Finding the Fourth Proportional to 30.87, 42.61 and 21.67

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Solution

The fourth proportional to 30.87, 42.61 and 21.67 is: 29.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.87 : 42.61 = 21.67 : x
  2. Step 2: Convert to fraction form
    30.87/42.61 = 21.67/x
  3. Step 3: Cross multiply
    30.87x = 42.61 × 21.67
  4. Step 4: Simplify right side
    30.87x = 923.36
  5. Step 5: Solve for x
    x = 923.36/30.87
  6. Step 6: Final answer
    x = 29.91

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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.