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Finding the Fourth Proportional to 853.80, 1,278.90 and 691.80

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Solution

The fourth proportional to 853.80, 1,278.90 and 691.80 is: 1,036.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.80 : 1,278.90 = 691.80 : x
  2. Step 2: Convert to fraction form
    853.80/1,278.90 = 691.80/x
  3. Step 3: Cross multiply
    853.80x = 1,278.90 × 691.80
  4. Step 4: Simplify right side
    853.80x = 884,743.02
  5. Step 5: Solve for x
    x = 884,743.02/853.80
  6. Step 6: Final answer
    x = 1,036.24

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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.