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Finding the Fourth Proportional to 811.28, 1,217.94 and 690.31

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Solution

The fourth proportional to 811.28, 1,217.94 and 690.31 is: 1,036.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.28 : 1,217.94 = 690.31 : x
  2. Step 2: Convert to fraction form
    811.28/1,217.94 = 690.31/x
  3. Step 3: Cross multiply
    811.28x = 1,217.94 × 690.31
  4. Step 4: Simplify right side
    811.28x = 840,753.12
  5. Step 5: Solve for x
    x = 840,753.12/811.28
  6. Step 6: Final answer
    x = 1,036.34

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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.