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Finding the Fourth Proportional to 989.38, 1,365.36 and 640.67

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Solution

The fourth proportional to 989.38, 1,365.36 and 640.67 is: 884.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.38 : 1,365.36 = 640.67 : x
  2. Step 2: Convert to fraction form
    989.38/1,365.36 = 640.67/x
  3. Step 3: Cross multiply
    989.38x = 1,365.36 × 640.67
  4. Step 4: Simplify right side
    989.38x = 874,745.19
  5. Step 5: Solve for x
    x = 874,745.19/989.38
  6. Step 6: Final answer
    x = 884.14

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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.