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Finding the Fourth Proportional to 1,209.35, 1,811.65 and 687.79

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Solution

The fourth proportional to 1,209.35, 1,811.65 and 687.79 is: 1,030.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.35 : 1,811.65 = 687.79 : x
  2. Step 2: Convert to fraction form
    1,209.35/1,811.65 = 687.79/x
  3. Step 3: Cross multiply
    1,209.35x = 1,811.65 × 687.79
  4. Step 4: Simplify right side
    1,209.35x = 1,246,034.75
  5. Step 5: Solve for x
    x = 1,246,034.75/1,209.35
  6. Step 6: Final answer
    x = 1,030.33

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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.