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Finding the Fourth Proportional to 840.42, 1,261.26 and 320.78

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Solution

The fourth proportional to 840.42, 1,261.26 and 320.78 is: 481.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.42 : 1,261.26 = 320.78 : x
  2. Step 2: Convert to fraction form
    840.42/1,261.26 = 320.78/x
  3. Step 3: Cross multiply
    840.42x = 1,261.26 × 320.78
  4. Step 4: Simplify right side
    840.42x = 404,590.14
  5. Step 5: Solve for x
    x = 404,590.14/840.42
  6. Step 6: Final answer
    x = 481.41

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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.