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Finding the Fourth Proportional to 30.96, 42.60 and 28.20

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Solution

The fourth proportional to 30.96, 42.60 and 28.20 is: 38.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.96 : 42.60 = 28.20 : x
  2. Step 2: Convert to fraction form
    30.96/42.60 = 28.20/x
  3. Step 3: Cross multiply
    30.96x = 42.60 × 28.20
  4. Step 4: Simplify right side
    30.96x = 1,201.32
  5. Step 5: Solve for x
    x = 1,201.32/30.96
  6. Step 6: Final answer
    x = 38.80

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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.