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Finding the Fourth Proportional to 15.81, 21.80 and 13.22

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Solution

The fourth proportional to 15.81, 21.80 and 13.22 is: 18.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.81 : 21.80 = 13.22 : x
  2. Step 2: Convert to fraction form
    15.81/21.80 = 13.22/x
  3. Step 3: Cross multiply
    15.81x = 21.80 × 13.22
  4. Step 4: Simplify right side
    15.81x = 288.20
  5. Step 5: Solve for x
    x = 288.20/15.81
  6. Step 6: Final answer
    x = 18.23

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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.