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Finding the Fourth Proportional to 718.28, 990.88 and 485

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Solution

The fourth proportional to 718.28, 990.88 and 485 is: 669.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.28 : 990.88 = 485 : x
  2. Step 2: Convert to fraction form
    718.28/990.88 = 485/x
  3. Step 3: Cross multiply
    718.28x = 990.88 × 485
  4. Step 4: Simplify right side
    718.28x = 480,576.80
  5. Step 5: Solve for x
    x = 480,576.80/718.28
  6. Step 6: Final answer
    x = 669.07

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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.