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Finding the Fourth Proportional to 21.01, 31.55 and 13.79

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Solution

The fourth proportional to 21.01, 31.55 and 13.79 is: 20.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.01 : 31.55 = 13.79 : x
  2. Step 2: Convert to fraction form
    21.01/31.55 = 13.79/x
  3. Step 3: Cross multiply
    21.01x = 31.55 × 13.79
  4. Step 4: Simplify right side
    21.01x = 435.07
  5. Step 5: Solve for x
    x = 435.07/21.01
  6. Step 6: Final answer
    x = 20.71

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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.