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Finding the Fourth Proportional to 987.31, 1,361.72 and 637.39

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Solution

The fourth proportional to 987.31, 1,361.72 and 637.39 is: 879.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.31 : 1,361.72 = 637.39 : x
  2. Step 2: Convert to fraction form
    987.31/1,361.72 = 637.39/x
  3. Step 3: Cross multiply
    987.31x = 1,361.72 × 637.39
  4. Step 4: Simplify right side
    987.31x = 867,950.01
  5. Step 5: Solve for x
    x = 867,950.01/987.31
  6. Step 6: Final answer
    x = 879.10

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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.