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Finding the Fourth Proportional to 15.21, 20.81 and 15.17

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Solution

The fourth proportional to 15.21, 20.81 and 15.17 is: 20.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.21 : 20.81 = 15.17 : x
  2. Step 2: Convert to fraction form
    15.21/20.81 = 15.17/x
  3. Step 3: Cross multiply
    15.21x = 20.81 × 15.17
  4. Step 4: Simplify right side
    15.21x = 315.51
  5. Step 5: Solve for x
    x = 315.51/15.21
  6. Step 6: Final answer
    x = 20.74

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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.