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Finding the Fourth Proportional to 70.78, 106.21 and 47.90

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Solution

The fourth proportional to 70.78, 106.21 and 47.90 is: 71.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.78 : 106.21 = 47.90 : x
  2. Step 2: Convert to fraction form
    70.78/106.21 = 47.90/x
  3. Step 3: Cross multiply
    70.78x = 106.21 × 47.90
  4. Step 4: Simplify right side
    70.78x = 5,087.51
  5. Step 5: Solve for x
    x = 5,087.51/70.78
  6. Step 6: Final answer
    x = 71.88

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.