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Finding the Fourth Proportional to 990.31, 1,485.97 and 661.47

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Solution

The fourth proportional to 990.31, 1,485.97 and 661.47 is: 992.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.31 : 1,485.97 = 661.47 : x
  2. Step 2: Convert to fraction form
    990.31/1,485.97 = 661.47/x
  3. Step 3: Cross multiply
    990.31x = 1,485.97 × 661.47
  4. Step 4: Simplify right side
    990.31x = 982,922.92
  5. Step 5: Solve for x
    x = 982,922.92/990.31
  6. Step 6: Final answer
    x = 992.54

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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.