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Finding the Fourth Proportional to 15.40, 21.23 and 11.72

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Solution

The fourth proportional to 15.40, 21.23 and 11.72 is: 16.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.40 : 21.23 = 11.72 : x
  2. Step 2: Convert to fraction form
    15.40/21.23 = 11.72/x
  3. Step 3: Cross multiply
    15.40x = 21.23 × 11.72
  4. Step 4: Simplify right side
    15.40x = 248.90
  5. Step 5: Solve for x
    x = 248.90/15.40
  6. Step 6: Final answer
    x = 16.16

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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.