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Finding the Fourth Proportional to 853.21, 1,279.14 and 420.13

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Solution

The fourth proportional to 853.21, 1,279.14 and 420.13 is: 629.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.21 : 1,279.14 = 420.13 : x
  2. Step 2: Convert to fraction form
    853.21/1,279.14 = 420.13/x
  3. Step 3: Cross multiply
    853.21x = 1,279.14 × 420.13
  4. Step 4: Simplify right side
    853.21x = 537,405.09
  5. Step 5: Solve for x
    x = 537,405.09/853.21
  6. Step 6: Final answer
    x = 629.86

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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.