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Finding the Fourth Proportional to 30.72, 45.60 and 28.72

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Solution

The fourth proportional to 30.72, 45.60 and 28.72 is: 42.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.72 : 45.60 = 28.72 : x
  2. Step 2: Convert to fraction form
    30.72/45.60 = 28.72/x
  3. Step 3: Cross multiply
    30.72x = 45.60 × 28.72
  4. Step 4: Simplify right side
    30.72x = 1,309.63
  5. Step 5: Solve for x
    x = 1,309.63/30.72
  6. Step 6: Final answer
    x = 42.63

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Why These Related Problems?

These problems maintain the same ratio (1.48) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.