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Finding the Fourth Proportional to 30.84, 42.57 and 28.90

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Solution

The fourth proportional to 30.84, 42.57 and 28.90 is: 39.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.84 : 42.57 = 28.90 : x
  2. Step 2: Convert to fraction form
    30.84/42.57 = 28.90/x
  3. Step 3: Cross multiply
    30.84x = 42.57 × 28.90
  4. Step 4: Simplify right side
    30.84x = 1,230.27
  5. Step 5: Solve for x
    x = 1,230.27/30.84
  6. Step 6: Final answer
    x = 39.90

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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.