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Finding the Fourth Proportional to 989.60, 1,367.29 and 781.37

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Solution

The fourth proportional to 989.60, 1,367.29 and 781.37 is: 1,079.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.60 : 1,367.29 = 781.37 : x
  2. Step 2: Convert to fraction form
    989.60/1,367.29 = 781.37/x
  3. Step 3: Cross multiply
    989.60x = 1,367.29 × 781.37
  4. Step 4: Simplify right side
    989.60x = 1,068,359.39
  5. Step 5: Solve for x
    x = 1,068,359.39/989.60
  6. Step 6: Final answer
    x = 1,079.59

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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.