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Finding the Fourth Proportional to 15.45, 21.31 and 11.80

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Solution

The fourth proportional to 15.45, 21.31 and 11.80 is: 16.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.45 : 21.31 = 11.80 : x
  2. Step 2: Convert to fraction form
    15.45/21.31 = 11.80/x
  3. Step 3: Cross multiply
    15.45x = 21.31 × 11.80
  4. Step 4: Simplify right side
    15.45x = 251.46
  5. Step 5: Solve for x
    x = 251.46/15.45
  6. Step 6: Final answer
    x = 16.28

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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.