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Finding the Fourth Proportional to 990.80, 1,485.80 and 442.61

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Solution

The fourth proportional to 990.80, 1,485.80 and 442.61 is: 663.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.80 : 1,485.80 = 442.61 : x
  2. Step 2: Convert to fraction form
    990.80/1,485.80 = 442.61/x
  3. Step 3: Cross multiply
    990.80x = 1,485.80 × 442.61
  4. Step 4: Simplify right side
    990.80x = 657,621.96
  5. Step 5: Solve for x
    x = 657,621.96/990.80
  6. Step 6: Final answer
    x = 663.73

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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.