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Finding the Fourth Proportional to 1,121.99, 1,682.79 and 428.67

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Solution

The fourth proportional to 1,121.99, 1,682.79 and 428.67 is: 642.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.99 : 1,682.79 = 428.67 : x
  2. Step 2: Convert to fraction form
    1,121.99/1,682.79 = 428.67/x
  3. Step 3: Cross multiply
    1,121.99x = 1,682.79 × 428.67
  4. Step 4: Simplify right side
    1,121.99x = 721,361.59
  5. Step 5: Solve for x
    x = 721,361.59/1,121.99
  6. Step 6: Final answer
    x = 642.93

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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.