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Finding the Fourth Proportional to 38.69, 53.40 and 21.21

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Solution

The fourth proportional to 38.69, 53.40 and 21.21 is: 29.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.69 : 53.40 = 21.21 : x
  2. Step 2: Convert to fraction form
    38.69/53.40 = 21.21/x
  3. Step 3: Cross multiply
    38.69x = 53.40 × 21.21
  4. Step 4: Simplify right side
    38.69x = 1,132.57
  5. Step 5: Solve for x
    x = 1,132.57/38.69
  6. Step 6: Final answer
    x = 29.27

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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.