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Finding the Fourth Proportional to 38.91, 53.69 and 21.66

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Solution

The fourth proportional to 38.91, 53.69 and 21.66 is: 29.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.91 : 53.69 = 21.66 : x
  2. Step 2: Convert to fraction form
    38.91/53.69 = 21.66/x
  3. Step 3: Cross multiply
    38.91x = 53.69 × 21.66
  4. Step 4: Simplify right side
    38.91x = 1,162.74
  5. Step 5: Solve for x
    x = 1,162.74/38.91
  6. Step 6: Final answer
    x = 29.89

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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.