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Finding the Fourth Proportional to 21.81, 30.13 and 21.66

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Solution

The fourth proportional to 21.81, 30.13 and 21.66 is: 29.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.81 : 30.13 = 21.66 : x
  2. Step 2: Convert to fraction form
    21.81/30.13 = 21.66/x
  3. Step 3: Cross multiply
    21.81x = 30.13 × 21.66
  4. Step 4: Simplify right side
    21.81x = 652.51
  5. Step 5: Solve for x
    x = 652.51/21.81
  6. Step 6: Final answer
    x = 29.92

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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.