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Finding the Fourth Proportional to 811.10, 1,215.74 and 399.36

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Solution

The fourth proportional to 811.10, 1,215.74 and 399.36 is: 598.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.10 : 1,215.74 = 399.36 : x
  2. Step 2: Convert to fraction form
    811.10/1,215.74 = 399.36/x
  3. Step 3: Cross multiply
    811.10x = 1,215.74 × 399.36
  4. Step 4: Simplify right side
    811.10x = 485,517.93
  5. Step 5: Solve for x
    x = 485,517.93/811.10
  6. Step 6: Final answer
    x = 598.59

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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.