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Finding the Fourth Proportional to 1,203.80, 1,661.40 and 680

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Solution

The fourth proportional to 1,203.80, 1,661.40 and 680 is: 938.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,203.80 : 1,661.40 = 680 : x
  2. Step 2: Convert to fraction form
    1,203.80/1,661.40 = 680/x
  3. Step 3: Cross multiply
    1,203.80x = 1,661.40 × 680
  4. Step 4: Simplify right side
    1,203.80x = 1,129,752
  5. Step 5: Solve for x
    x = 1,129,752/1,203.80
  6. Step 6: Final answer
    x = 938.49

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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.