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Finding the Fourth Proportional to 28.36, 42.59 and 20.78

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Solution

The fourth proportional to 28.36, 42.59 and 20.78 is: 31.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.36 : 42.59 = 20.78 : x
  2. Step 2: Convert to fraction form
    28.36/42.59 = 20.78/x
  3. Step 3: Cross multiply
    28.36x = 42.59 × 20.78
  4. Step 4: Simplify right side
    28.36x = 885.02
  5. Step 5: Solve for x
    x = 885.02/28.36
  6. Step 6: Final answer
    x = 31.21

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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.