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Finding the Fourth Proportional to 1,311.72, 1,811.01 and 815.08

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Solution

The fourth proportional to 1,311.72, 1,811.01 and 815.08 is: 1,125.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.72 : 1,811.01 = 815.08 : x
  2. Step 2: Convert to fraction form
    1,311.72/1,811.01 = 815.08/x
  3. Step 3: Cross multiply
    1,311.72x = 1,811.01 × 815.08
  4. Step 4: Simplify right side
    1,311.72x = 1,476,108.98
  5. Step 5: Solve for x
    x = 1,476,108.98/1,311.72
  6. Step 6: Final answer
    x = 1,125.33

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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.