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Finding the Fourth Proportional to 15.21, 20.99 and 9.75

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Solution

The fourth proportional to 15.21, 20.99 and 9.75 is: 13.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.21 : 20.99 = 9.75 : x
  2. Step 2: Convert to fraction form
    15.21/20.99 = 9.75/x
  3. Step 3: Cross multiply
    15.21x = 20.99 × 9.75
  4. Step 4: Simplify right side
    15.21x = 204.65
  5. Step 5: Solve for x
    x = 204.65/15.21
  6. Step 6: Final answer
    x = 13.46

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.