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Finding the Fourth Proportional to 811, 1,215.40 and 445.96

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Solution

The fourth proportional to 811, 1,215.40 and 445.96 is: 668.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    811 : 1,215.40 = 445.96 : x
  2. Step 2: Convert to fraction form
    811/1,215.40 = 445.96/x
  3. Step 3: Cross multiply
    811x = 1,215.40 × 445.96
  4. Step 4: Simplify right side
    811x = 542,019.78
  5. Step 5: Solve for x
    x = 542,019.78/811
  6. Step 6: Final answer
    x = 668.34

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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.