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Finding the Fourth Proportional to 986.60, 1,478.28 and 639.92

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Solution

The fourth proportional to 986.60, 1,478.28 and 639.92 is: 958.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    986.60 : 1,478.28 = 639.92 : x
  2. Step 2: Convert to fraction form
    986.60/1,478.28 = 639.92/x
  3. Step 3: Cross multiply
    986.60x = 1,478.28 × 639.92
  4. Step 4: Simplify right side
    986.60x = 945,980.94
  5. Step 5: Solve for x
    x = 945,980.94/986.60
  6. Step 6: Final answer
    x = 958.83

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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.