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Finding the Fourth Proportional to 15.21, 20.85 and 15.18

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Solution

The fourth proportional to 15.21, 20.85 and 15.18 is: 20.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.21 : 20.85 = 15.18 : x
  2. Step 2: Convert to fraction form
    15.21/20.85 = 15.18/x
  3. Step 3: Cross multiply
    15.21x = 20.85 × 15.18
  4. Step 4: Simplify right side
    15.21x = 316.50
  5. Step 5: Solve for x
    x = 316.50/15.21
  6. Step 6: Final answer
    x = 20.81

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.