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Finding the Fourth Proportional to 28.05, 38.71 and 21.15

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Solution

The fourth proportional to 28.05, 38.71 and 21.15 is: 29.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.05 : 38.71 = 21.15 : x
  2. Step 2: Convert to fraction form
    28.05/38.71 = 21.15/x
  3. Step 3: Cross multiply
    28.05x = 38.71 × 21.15
  4. Step 4: Simplify right side
    28.05x = 818.72
  5. Step 5: Solve for x
    x = 818.72/28.05
  6. Step 6: Final answer
    x = 29.19

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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.