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Finding the Fourth Proportional to 811.14, 1,215.56 and 399.87

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Solution

The fourth proportional to 811.14, 1,215.56 and 399.87 is: 599.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.14 : 1,215.56 = 399.87 : x
  2. Step 2: Convert to fraction form
    811.14/1,215.56 = 399.87/x
  3. Step 3: Cross multiply
    811.14x = 1,215.56 × 399.87
  4. Step 4: Simplify right side
    811.14x = 486,063.98
  5. Step 5: Solve for x
    x = 486,063.98/811.14
  6. Step 6: Final answer
    x = 599.24

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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.