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Finding the Fourth Proportional to 1,121.31, 1,681.38 and 427.77

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Solution

The fourth proportional to 1,121.31, 1,681.38 and 427.77 is: 641.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.31 : 1,681.38 = 427.77 : x
  2. Step 2: Convert to fraction form
    1,121.31/1,681.38 = 427.77/x
  3. Step 3: Cross multiply
    1,121.31x = 1,681.38 × 427.77
  4. Step 4: Simplify right side
    1,121.31x = 719,243.92
  5. Step 5: Solve for x
    x = 719,243.92/1,121.31
  6. Step 6: Final answer
    x = 641.43

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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.