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Finding the Fourth Proportional to 30.94, 42.69 and 28.21

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Solution

The fourth proportional to 30.94, 42.69 and 28.21 is: 38.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.94 : 42.69 = 28.21 : x
  2. Step 2: Convert to fraction form
    30.94/42.69 = 28.21/x
  3. Step 3: Cross multiply
    30.94x = 42.69 × 28.21
  4. Step 4: Simplify right side
    30.94x = 1,204.28
  5. Step 5: Solve for x
    x = 1,204.28/30.94
  6. Step 6: Final answer
    x = 38.92

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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.