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Finding the Fourth Proportional to 989.40, 1,371.62 and 936.74

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Solution

The fourth proportional to 989.40, 1,371.62 and 936.74 is: 1,298.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.40 : 1,371.62 = 936.74 : x
  2. Step 2: Convert to fraction form
    989.40/1,371.62 = 936.74/x
  3. Step 3: Cross multiply
    989.40x = 1,371.62 × 936.74
  4. Step 4: Simplify right side
    989.40x = 1,284,847.62
  5. Step 5: Solve for x
    x = 1,284,847.62/989.40
  6. Step 6: Final answer
    x = 1,298.61

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.