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Finding the Fourth Proportional to 987.43, 1,361.78 and 637.75

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Solution

The fourth proportional to 987.43, 1,361.78 and 637.75 is: 879.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.43 : 1,361.78 = 637.75 : x
  2. Step 2: Convert to fraction form
    987.43/1,361.78 = 637.75/x
  3. Step 3: Cross multiply
    987.43x = 1,361.78 × 637.75
  4. Step 4: Simplify right side
    987.43x = 868,472.01
  5. Step 5: Solve for x
    x = 868,472.01/987.43
  6. Step 6: Final answer
    x = 879.53

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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.