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Finding the Fourth Proportional to 20.70, 31.08 and 13.08

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Solution

The fourth proportional to 20.70, 31.08 and 13.08 is: 19.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.70 : 31.08 = 13.08 : x
  2. Step 2: Convert to fraction form
    20.70/31.08 = 13.08/x
  3. Step 3: Cross multiply
    20.70x = 31.08 × 13.08
  4. Step 4: Simplify right side
    20.70x = 406.53
  5. Step 5: Solve for x
    x = 406.53/20.70
  6. Step 6: Final answer
    x = 19.64

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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.