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Finding the Fourth Proportional to 853.86, 1,279.39 and 821.87

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Solution

The fourth proportional to 853.86, 1,279.39 and 821.87 is: 1,231.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.86 : 1,279.39 = 821.87 : x
  2. Step 2: Convert to fraction form
    853.86/1,279.39 = 821.87/x
  3. Step 3: Cross multiply
    853.86x = 1,279.39 × 821.87
  4. Step 4: Simplify right side
    853.86x = 1,051,492.26
  5. Step 5: Solve for x
    x = 1,051,492.26/853.86
  6. Step 6: Final answer
    x = 1,231.46

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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.