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Finding the Fourth Proportional to 2,121.70, 3,182.86 and 661

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Solution

The fourth proportional to 2,121.70, 3,182.86 and 661 is: 991.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,121.70 : 3,182.86 = 661 : x
  2. Step 2: Convert to fraction form
    2,121.70/3,182.86 = 661/x
  3. Step 3: Cross multiply
    2,121.70x = 3,182.86 × 661
  4. Step 4: Simplify right side
    2,121.70x = 2,103,870.46
  5. Step 5: Solve for x
    x = 2,103,870.46/2,121.70
  6. Step 6: Final answer
    x = 991.60

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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.