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Finding the Fourth Proportional to 28.15, 42.15 and 20.53

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Solution

The fourth proportional to 28.15, 42.15 and 20.53 is: 30.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.15 : 42.15 = 20.53 : x
  2. Step 2: Convert to fraction form
    28.15/42.15 = 20.53/x
  3. Step 3: Cross multiply
    28.15x = 42.15 × 20.53
  4. Step 4: Simplify right side
    28.15x = 865.34
  5. Step 5: Solve for x
    x = 865.34/28.15
  6. Step 6: Final answer
    x = 30.74

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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.