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Finding the Fourth Proportional to 853.56, 1,281.80 and 811

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Solution

The fourth proportional to 853.56, 1,281.80 and 811 is: 1,217.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.56 : 1,281.80 = 811 : x
  2. Step 2: Convert to fraction form
    853.56/1,281.80 = 811/x
  3. Step 3: Cross multiply
    853.56x = 1,281.80 × 811
  4. Step 4: Simplify right side
    853.56x = 1,039,539.80
  5. Step 5: Solve for x
    x = 1,039,539.80/853.56
  6. Step 6: Final answer
    x = 1,217.89

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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.