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Finding the Fourth Proportional to 1,389.20, 2,082.21 and 657.74

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Solution

The fourth proportional to 1,389.20, 2,082.21 and 657.74 is: 985.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.20 : 2,082.21 = 657.74 : x
  2. Step 2: Convert to fraction form
    1,389.20/2,082.21 = 657.74/x
  3. Step 3: Cross multiply
    1,389.20x = 2,082.21 × 657.74
  4. Step 4: Simplify right side
    1,389.20x = 1,369,552.81
  5. Step 5: Solve for x
    x = 1,369,552.81/1,389.20
  6. Step 6: Final answer
    x = 985.86

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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.