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Finding the Fourth Proportional to 27.80, 38.38 and 20.90

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Solution

The fourth proportional to 27.80, 38.38 and 20.90 is: 28.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    27.80 : 38.38 = 20.90 : x
  2. Step 2: Convert to fraction form
    27.80/38.38 = 20.90/x
  3. Step 3: Cross multiply
    27.80x = 38.38 × 20.90
  4. Step 4: Simplify right side
    27.80x = 802.07
  5. Step 5: Solve for x
    x = 802.07/27.80
  6. Step 6: Final answer
    x = 28.85

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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.