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Finding the Fourth Proportional to 51.23, 76.80 and 20.81

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Solution

The fourth proportional to 51.23, 76.80 and 20.81 is: 31.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.23 : 76.80 = 20.81 : x
  2. Step 2: Convert to fraction form
    51.23/76.80 = 20.81/x
  3. Step 3: Cross multiply
    51.23x = 76.80 × 20.81
  4. Step 4: Simplify right side
    51.23x = 1,597.93
  5. Step 5: Solve for x
    x = 1,597.93/51.23
  6. Step 6: Final answer
    x = 31.19

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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.