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Finding the Fourth Proportional to 840.76, 1,261.32 and 780.76

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Solution

The fourth proportional to 840.76, 1,261.32 and 780.76 is: 1,171.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.76 : 1,261.32 = 780.76 : x
  2. Step 2: Convert to fraction form
    840.76/1,261.32 = 780.76/x
  3. Step 3: Cross multiply
    840.76x = 1,261.32 × 780.76
  4. Step 4: Simplify right side
    840.76x = 984,788.20
  5. Step 5: Solve for x
    x = 984,788.20/840.76
  6. Step 6: Final answer
    x = 1,171.31

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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.