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Finding the Fourth Proportional to 638.45, 881.18 and 389.99

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Solution

The fourth proportional to 638.45, 881.18 and 389.99 is: 538.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.45 : 881.18 = 389.99 : x
  2. Step 2: Convert to fraction form
    638.45/881.18 = 389.99/x
  3. Step 3: Cross multiply
    638.45x = 881.18 × 389.99
  4. Step 4: Simplify right side
    638.45x = 343,645.03
  5. Step 5: Solve for x
    x = 343,645.03/638.45
  6. Step 6: Final answer
    x = 538.25

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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.