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Finding the Fourth Proportional to 1,311.80, 1,808.34 and 869

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Solution

The fourth proportional to 1,311.80, 1,808.34 and 869 is: 1,197.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.80 : 1,808.34 = 869 : x
  2. Step 2: Convert to fraction form
    1,311.80/1,808.34 = 869/x
  3. Step 3: Cross multiply
    1,311.80x = 1,808.34 × 869
  4. Step 4: Simplify right side
    1,311.80x = 1,571,447.46
  5. Step 5: Solve for x
    x = 1,571,447.46/1,311.80
  6. Step 6: Final answer
    x = 1,197.93

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.