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Finding the Fourth Proportional to 718.56, 990.09 and 485.28

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Solution

The fourth proportional to 718.56, 990.09 and 485.28 is: 668.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.56 : 990.09 = 485.28 : x
  2. Step 2: Convert to fraction form
    718.56/990.09 = 485.28/x
  3. Step 3: Cross multiply
    718.56x = 990.09 × 485.28
  4. Step 4: Simplify right side
    718.56x = 480,470.88
  5. Step 5: Solve for x
    x = 480,470.88/718.56
  6. Step 6: Final answer
    x = 668.66

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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.