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Finding the Fourth Proportional to 1,209.21, 1,668.78 and 685.28

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Solution

The fourth proportional to 1,209.21, 1,668.78 and 685.28 is: 945.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.21 : 1,668.78 = 685.28 : x
  2. Step 2: Convert to fraction form
    1,209.21/1,668.78 = 685.28/x
  3. Step 3: Cross multiply
    1,209.21x = 1,668.78 × 685.28
  4. Step 4: Simplify right side
    1,209.21x = 1,143,573.21
  5. Step 5: Solve for x
    x = 1,143,573.21/1,209.21
  6. Step 6: Final answer
    x = 945.72

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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.