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Finding the Fourth Proportional to 990.31, 1,366.59 and 640.99

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Solution

The fourth proportional to 990.31, 1,366.59 and 640.99 is: 884.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.31 : 1,366.59 = 640.99 : x
  2. Step 2: Convert to fraction form
    990.31/1,366.59 = 640.99/x
  3. Step 3: Cross multiply
    990.31x = 1,366.59 × 640.99
  4. Step 4: Simplify right side
    990.31x = 875,970.52
  5. Step 5: Solve for x
    x = 875,970.52/990.31
  6. Step 6: Final answer
    x = 884.54

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.