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Finding the Fourth Proportional to 1,122.42, 1,683.32 and 428.61

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Solution

The fourth proportional to 1,122.42, 1,683.32 and 428.61 is: 642.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,122.42 : 1,683.32 = 428.61 : x
  2. Step 2: Convert to fraction form
    1,122.42/1,683.32 = 428.61/x
  3. Step 3: Cross multiply
    1,122.42x = 1,683.32 × 428.61
  4. Step 4: Simplify right side
    1,122.42x = 721,485.64
  5. Step 5: Solve for x
    x = 721,485.64/1,122.42
  6. Step 6: Final answer
    x = 642.79

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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.