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Finding the Fourth Proportional to 47.20, 70.40 and 42.88

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Solution

The fourth proportional to 47.20, 70.40 and 42.88 is: 63.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.20 : 70.40 = 42.88 : x
  2. Step 2: Convert to fraction form
    47.20/70.40 = 42.88/x
  3. Step 3: Cross multiply
    47.20x = 70.40 × 42.88
  4. Step 4: Simplify right side
    47.20x = 3,018.75
  5. Step 5: Solve for x
    x = 3,018.75/47.20
  6. Step 6: Final answer
    x = 63.96

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.