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Finding the Fourth Proportional to 30.72, 42.39 and 16.90

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Solution

The fourth proportional to 30.72, 42.39 and 16.90 is: 23.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.72 : 42.39 = 16.90 : x
  2. Step 2: Convert to fraction form
    30.72/42.39 = 16.90/x
  3. Step 3: Cross multiply
    30.72x = 42.39 × 16.90
  4. Step 4: Simplify right side
    30.72x = 716.31
  5. Step 5: Solve for x
    x = 716.31/30.72
  6. Step 6: Final answer
    x = 23.32

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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.