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Finding the Fourth Proportional to 990.90, 1,485.54 and 665.28

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Solution

The fourth proportional to 990.90, 1,485.54 and 665.28 is: 997.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.90 : 1,485.54 = 665.28 : x
  2. Step 2: Convert to fraction form
    990.90/1,485.54 = 665.28/x
  3. Step 3: Cross multiply
    990.90x = 1,485.54 × 665.28
  4. Step 4: Simplify right side
    990.90x = 988,300.05
  5. Step 5: Solve for x
    x = 988,300.05/990.90
  6. Step 6: Final answer
    x = 997.38

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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.