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Finding the Fourth Proportional to 389.85, 538 and 215.20

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Solution

The fourth proportional to 389.85, 538 and 215.20 is: 296.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.85 : 538 = 215.20 : x
  2. Step 2: Convert to fraction form
    389.85/538 = 215.20/x
  3. Step 3: Cross multiply
    389.85x = 538 × 215.20
  4. Step 4: Simplify right side
    389.85x = 115,777.60
  5. Step 5: Solve for x
    x = 115,777.60/389.85
  6. Step 6: Final answer
    x = 296.98

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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.