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Finding the Fourth Proportional to 390.43, 538.89 and 231.05

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Solution

The fourth proportional to 390.43, 538.89 and 231.05 is: 318.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.43 : 538.89 = 231.05 : x
  2. Step 2: Convert to fraction form
    390.43/538.89 = 231.05/x
  3. Step 3: Cross multiply
    390.43x = 538.89 × 231.05
  4. Step 4: Simplify right side
    390.43x = 124,510.53
  5. Step 5: Solve for x
    x = 124,510.53/390.43
  6. Step 6: Final answer
    x = 318.91

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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.