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Finding the Fourth Proportional to 990.80, 1,486.56 and 442.72

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Solution

The fourth proportional to 990.80, 1,486.56 and 442.72 is: 664.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.80 : 1,486.56 = 442.72 : x
  2. Step 2: Convert to fraction form
    990.80/1,486.56 = 442.72/x
  3. Step 3: Cross multiply
    990.80x = 1,486.56 × 442.72
  4. Step 4: Simplify right side
    990.80x = 658,129.84
  5. Step 5: Solve for x
    x = 658,129.84/990.80
  6. Step 6: Final answer
    x = 664.24

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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.