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Finding the Fourth Proportional to 15.47, 21.28 and 13.80

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Solution

The fourth proportional to 15.47, 21.28 and 13.80 is: 18.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.47 : 21.28 = 13.80 : x
  2. Step 2: Convert to fraction form
    15.47/21.28 = 13.80/x
  3. Step 3: Cross multiply
    15.47x = 21.28 × 13.80
  4. Step 4: Simplify right side
    15.47x = 293.66
  5. Step 5: Solve for x
    x = 293.66/15.47
  6. Step 6: Final answer
    x = 18.98

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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.