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Finding the Fourth Proportional to 815.21, 1,222.81 and 198.91

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Solution

The fourth proportional to 815.21, 1,222.81 and 198.91 is: 298.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.21 : 1,222.81 = 198.91 : x
  2. Step 2: Convert to fraction form
    815.21/1,222.81 = 198.91/x
  3. Step 3: Cross multiply
    815.21x = 1,222.81 × 198.91
  4. Step 4: Simplify right side
    815.21x = 243,225.58
  5. Step 5: Solve for x
    x = 243,225.58/815.21
  6. Step 6: Final answer
    x = 298.36

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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.