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Finding the Fourth Proportional to 840.72, 1,261.76 and 679.43

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Solution

The fourth proportional to 840.72, 1,261.76 and 679.43 is: 1,019.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.72 : 1,261.76 = 679.43 : x
  2. Step 2: Convert to fraction form
    840.72/1,261.76 = 679.43/x
  3. Step 3: Cross multiply
    840.72x = 1,261.76 × 679.43
  4. Step 4: Simplify right side
    840.72x = 857,277.60
  5. Step 5: Solve for x
    x = 857,277.60/840.72
  6. Step 6: Final answer
    x = 1,019.69

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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.