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Finding the Fourth Proportional to 990, 1,485.57 and 551.31

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Solution

The fourth proportional to 990, 1,485.57 and 551.31 is: 827.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    990 : 1,485.57 = 551.31 : x
  2. Step 2: Convert to fraction form
    990/1,485.57 = 551.31/x
  3. Step 3: Cross multiply
    990x = 1,485.57 × 551.31
  4. Step 4: Simplify right side
    990x = 819,009.60
  5. Step 5: Solve for x
    x = 819,009.60/990
  6. Step 6: Final answer
    x = 827.28

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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.