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Finding the Fourth Proportional to 986.39, 1,478.58 and 639.94

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Solution

The fourth proportional to 986.39, 1,478.58 and 639.94 is: 959.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    986.39 : 1,478.58 = 639.94 : x
  2. Step 2: Convert to fraction form
    986.39/1,478.58 = 639.94/x
  3. Step 3: Cross multiply
    986.39x = 1,478.58 × 639.94
  4. Step 4: Simplify right side
    986.39x = 946,201.93
  5. Step 5: Solve for x
    x = 946,201.93/986.39
  6. Step 6: Final answer
    x = 959.26

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.