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Finding the Fourth Proportional to 1,661.18, 2,491.89 and 428.58

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Solution

The fourth proportional to 1,661.18, 2,491.89 and 428.58 is: 642.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,661.18 : 2,491.89 = 428.58 : x
  2. Step 2: Convert to fraction form
    1,661.18/2,491.89 = 428.58/x
  3. Step 3: Cross multiply
    1,661.18x = 2,491.89 × 428.58
  4. Step 4: Simplify right side
    1,661.18x = 1,067,980.82
  5. Step 5: Solve for x
    x = 1,067,980.82/1,661.18
  6. Step 6: Final answer
    x = 642.91

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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.