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Finding the Fourth Proportional to 989.20, 1,361.64 and 902.80

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Solution

The fourth proportional to 989.20, 1,361.64 and 902.80 is: 1,242.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.20 : 1,361.64 = 902.80 : x
  2. Step 2: Convert to fraction form
    989.20/1,361.64 = 902.80/x
  3. Step 3: Cross multiply
    989.20x = 1,361.64 × 902.80
  4. Step 4: Simplify right side
    989.20x = 1,229,288.59
  5. Step 5: Solve for x
    x = 1,229,288.59/989.20
  6. Step 6: Final answer
    x = 1,242.71

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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.