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Finding the Fourth Proportional to 47.21, 70.79 and 20.15

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Solution

The fourth proportional to 47.21, 70.79 and 20.15 is: 30.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.21 : 70.79 = 20.15 : x
  2. Step 2: Convert to fraction form
    47.21/70.79 = 20.15/x
  3. Step 3: Cross multiply
    47.21x = 70.79 × 20.15
  4. Step 4: Simplify right side
    47.21x = 1,426.06
  5. Step 5: Solve for x
    x = 1,426.06/47.21
  6. Step 6: Final answer
    x = 30.21

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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.