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Finding the Fourth Proportional to 28.91, 39.90 and 21.99

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Solution

The fourth proportional to 28.91, 39.90 and 21.99 is: 30.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.91 : 39.90 = 21.99 : x
  2. Step 2: Convert to fraction form
    28.91/39.90 = 21.99/x
  3. Step 3: Cross multiply
    28.91x = 39.90 × 21.99
  4. Step 4: Simplify right side
    28.91x = 877.40
  5. Step 5: Solve for x
    x = 877.40/28.91
  6. Step 6: Final answer
    x = 30.35

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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.