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Finding the Fourth Proportional to 1,309.05, 1,808.09 and 978.94

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Solution

The fourth proportional to 1,309.05, 1,808.09 and 978.94 is: 1,352.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,309.05 : 1,808.09 = 978.94 : x
  2. Step 2: Convert to fraction form
    1,309.05/1,808.09 = 978.94/x
  3. Step 3: Cross multiply
    1,309.05x = 1,808.09 × 978.94
  4. Step 4: Simplify right side
    1,309.05x = 1,770,002.21
  5. Step 5: Solve for x
    x = 1,770,002.21/1,309.05
  6. Step 6: Final answer
    x = 1,352.13

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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.