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Finding the Fourth Proportional to 70.21, 105.38 and 39.79

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Solution

The fourth proportional to 70.21, 105.38 and 39.79 is: 59.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.21 : 105.38 = 39.79 : x
  2. Step 2: Convert to fraction form
    70.21/105.38 = 39.79/x
  3. Step 3: Cross multiply
    70.21x = 105.38 × 39.79
  4. Step 4: Simplify right side
    70.21x = 4,193.07
  5. Step 5: Solve for x
    x = 4,193.07/70.21
  6. Step 6: Final answer
    x = 59.72

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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.