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Finding the Fourth Proportional to 786.80, 1,179.39 and 421.49

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Solution

The fourth proportional to 786.80, 1,179.39 and 421.49 is: 631.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.80 : 1,179.39 = 421.49 : x
  2. Step 2: Convert to fraction form
    786.80/1,179.39 = 421.49/x
  3. Step 3: Cross multiply
    786.80x = 1,179.39 × 421.49
  4. Step 4: Simplify right side
    786.80x = 497,098.83
  5. Step 5: Solve for x
    x = 497,098.83/786.80
  6. Step 6: Final answer
    x = 631.80

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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.