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Finding the Fourth Proportional to 989.76, 1,485.24 and 442.20

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Solution

The fourth proportional to 989.76, 1,485.24 and 442.20 is: 663.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.76 : 1,485.24 = 442.20 : x
  2. Step 2: Convert to fraction form
    989.76/1,485.24 = 442.20/x
  3. Step 3: Cross multiply
    989.76x = 1,485.24 × 442.20
  4. Step 4: Simplify right side
    989.76x = 656,773.13
  5. Step 5: Solve for x
    x = 656,773.13/989.76
  6. Step 6: Final answer
    x = 663.57

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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.