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Finding the Fourth Proportional to 989.94, 1,485.62 and 579.20

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Solution

The fourth proportional to 989.94, 1,485.62 and 579.20 is: 869.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.94 : 1,485.62 = 579.20 : x
  2. Step 2: Convert to fraction form
    989.94/1,485.62 = 579.20/x
  3. Step 3: Cross multiply
    989.94x = 1,485.62 × 579.20
  4. Step 4: Simplify right side
    989.94x = 860,460.78
  5. Step 5: Solve for x
    x = 860,460.78/989.94
  6. Step 6: Final answer
    x = 869.20

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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.