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Finding the Fourth Proportional to 286.40, 431.30 and 257.85

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Solution

The fourth proportional to 286.40, 431.30 and 257.85 is: 388.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    286.40 : 431.30 = 257.85 : x
  2. Step 2: Convert to fraction form
    286.40/431.30 = 257.85/x
  3. Step 3: Cross multiply
    286.40x = 431.30 × 257.85
  4. Step 4: Simplify right side
    286.40x = 111,210.38
  5. Step 5: Solve for x
    x = 111,210.38/286.40
  6. Step 6: Final answer
    x = 388.30

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.