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Finding the Fourth Proportional to 30.70, 42.31 and 20.98

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Solution

The fourth proportional to 30.70, 42.31 and 20.98 is: 28.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.70 : 42.31 = 20.98 : x
  2. Step 2: Convert to fraction form
    30.70/42.31 = 20.98/x
  3. Step 3: Cross multiply
    30.70x = 42.31 × 20.98
  4. Step 4: Simplify right side
    30.70x = 887.66
  5. Step 5: Solve for x
    x = 887.66/30.70
  6. Step 6: Final answer
    x = 28.91

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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.