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Finding the Fourth Proportional to 1,208.78, 1,668.41 and 685.11

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Solution

The fourth proportional to 1,208.78, 1,668.41 and 685.11 is: 945.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,208.78 : 1,668.41 = 685.11 : x
  2. Step 2: Convert to fraction form
    1,208.78/1,668.41 = 685.11/x
  3. Step 3: Cross multiply
    1,208.78x = 1,668.41 × 685.11
  4. Step 4: Simplify right side
    1,208.78x = 1,143,040.95
  5. Step 5: Solve for x
    x = 1,143,040.95/1,208.78
  6. Step 6: Final answer
    x = 945.62

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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.