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Finding the Fourth Proportional to 1,276.78, 1,761.86 and 717.18

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Solution

The fourth proportional to 1,276.78, 1,761.86 and 717.18 is: 989.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,276.78 : 1,761.86 = 717.18 : x
  2. Step 2: Convert to fraction form
    1,276.78/1,761.86 = 717.18/x
  3. Step 3: Cross multiply
    1,276.78x = 1,761.86 × 717.18
  4. Step 4: Simplify right side
    1,276.78x = 1,263,570.75
  5. Step 5: Solve for x
    x = 1,263,570.75/1,276.78
  6. Step 6: Final answer
    x = 989.65

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.