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Finding the Fourth Proportional to 28.47, 39.30 and 21.99

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Solution

The fourth proportional to 28.47, 39.30 and 21.99 is: 30.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.47 : 39.30 = 21.99 : x
  2. Step 2: Convert to fraction form
    28.47/39.30 = 21.99/x
  3. Step 3: Cross multiply
    28.47x = 39.30 × 21.99
  4. Step 4: Simplify right side
    28.47x = 864.21
  5. Step 5: Solve for x
    x = 864.21/28.47
  6. Step 6: Final answer
    x = 30.36

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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.