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Finding the Fourth Proportional to 28.68, 42.88 and 20.99

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Solution

The fourth proportional to 28.68, 42.88 and 20.99 is: 31.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.68 : 42.88 = 20.99 : x
  2. Step 2: Convert to fraction form
    28.68/42.88 = 20.99/x
  3. Step 3: Cross multiply
    28.68x = 42.88 × 20.99
  4. Step 4: Simplify right side
    28.68x = 900.02
  5. Step 5: Solve for x
    x = 900.02/28.68
  6. Step 6: Final answer
    x = 31.39

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.