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Finding the Fourth Proportional to 30.65, 42.29 and 20.79

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Solution

The fourth proportional to 30.65, 42.29 and 20.79 is: 28.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.65 : 42.29 = 20.79 : x
  2. Step 2: Convert to fraction form
    30.65/42.29 = 20.79/x
  3. Step 3: Cross multiply
    30.65x = 42.29 × 20.79
  4. Step 4: Simplify right side
    30.65x = 879.21
  5. Step 5: Solve for x
    x = 879.21/30.65
  6. Step 6: Final answer
    x = 28.69

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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.