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Finding the Fourth Proportional to 808.40, 1,209.78 and 660.42

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Solution

The fourth proportional to 808.40, 1,209.78 and 660.42 is: 988.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    808.40 : 1,209.78 = 660.42 : x
  2. Step 2: Convert to fraction form
    808.40/1,209.78 = 660.42/x
  3. Step 3: Cross multiply
    808.40x = 1,209.78 × 660.42
  4. Step 4: Simplify right side
    808.40x = 798,962.91
  5. Step 5: Solve for x
    x = 798,962.91/808.40
  6. Step 6: Final answer
    x = 988.33

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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.