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Finding the Fourth Proportional to 638.81, 881.66 and 390.28

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Solution

The fourth proportional to 638.81, 881.66 and 390.28 is: 538.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.81 : 881.66 = 390.28 : x
  2. Step 2: Convert to fraction form
    638.81/881.66 = 390.28/x
  3. Step 3: Cross multiply
    638.81x = 881.66 × 390.28
  4. Step 4: Simplify right side
    638.81x = 344,093.04
  5. Step 5: Solve for x
    x = 344,093.04/638.81
  6. Step 6: Final answer
    x = 538.64

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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.