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Finding the Fourth Proportional to 20.70, 31.20 and 19.64

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Solution

The fourth proportional to 20.70, 31.20 and 19.64 is: 29.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.70 : 31.20 = 19.64 : x
  2. Step 2: Convert to fraction form
    20.70/31.20 = 19.64/x
  3. Step 3: Cross multiply
    20.70x = 31.20 × 19.64
  4. Step 4: Simplify right side
    20.70x = 612.61
  5. Step 5: Solve for x
    x = 612.61/20.70
  6. Step 6: Final answer
    x = 29.59

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.