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Finding the Fourth Proportional to 986.77, 1,361.87 and 637.21

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Solution

The fourth proportional to 986.77, 1,361.87 and 637.21 is: 879.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    986.77 : 1,361.87 = 637.21 : x
  2. Step 2: Convert to fraction form
    986.77/1,361.87 = 637.21/x
  3. Step 3: Cross multiply
    986.77x = 1,361.87 × 637.21
  4. Step 4: Simplify right side
    986.77x = 867,794.00
  5. Step 5: Solve for x
    x = 867,794.00/986.77
  6. Step 6: Final answer
    x = 879.43

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.