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Finding the Fourth Proportional to 1,223.18, 1,687.36 and 780.61

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Solution

The fourth proportional to 1,223.18, 1,687.36 and 780.61 is: 1,076.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,223.18 : 1,687.36 = 780.61 : x
  2. Step 2: Convert to fraction form
    1,223.18/1,687.36 = 780.61/x
  3. Step 3: Cross multiply
    1,223.18x = 1,687.36 × 780.61
  4. Step 4: Simplify right side
    1,223.18x = 1,317,170.09
  5. Step 5: Solve for x
    x = 1,317,170.09/1,223.18
  6. Step 6: Final answer
    x = 1,076.84

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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.