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Finding the Fourth Proportional to 990.09, 1,485 and 578.61

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Solution

The fourth proportional to 990.09, 1,485 and 578.61 is: 867.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.09 : 1,485 = 578.61 : x
  2. Step 2: Convert to fraction form
    990.09/1,485 = 578.61/x
  3. Step 3: Cross multiply
    990.09x = 1,485 × 578.61
  4. Step 4: Simplify right side
    990.09x = 859,235.85
  5. Step 5: Solve for x
    x = 859,235.85/990.09
  6. Step 6: Final answer
    x = 867.84

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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.