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Finding the Fourth Proportional to 28.58, 42.80 and 20.57

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Solution

The fourth proportional to 28.58, 42.80 and 20.57 is: 30.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.58 : 42.80 = 20.57 : x
  2. Step 2: Convert to fraction form
    28.58/42.80 = 20.57/x
  3. Step 3: Cross multiply
    28.58x = 42.80 × 20.57
  4. Step 4: Simplify right side
    28.58x = 880.08
  5. Step 5: Solve for x
    x = 880.08/28.58
  6. Step 6: Final answer
    x = 30.80

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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.