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Finding the Fourth Proportional to 30.88, 42.55 and 21.65

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Solution

The fourth proportional to 30.88, 42.55 and 21.65 is: 29.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.88 : 42.55 = 21.65 : x
  2. Step 2: Convert to fraction form
    30.88/42.55 = 21.65/x
  3. Step 3: Cross multiply
    30.88x = 42.55 × 21.65
  4. Step 4: Simplify right side
    30.88x = 921.21
  5. Step 5: Solve for x
    x = 921.21/30.88
  6. Step 6: Final answer
    x = 29.83

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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.