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Finding the Fourth Proportional to 390.70, 538.95 and 257.66

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Solution

The fourth proportional to 390.70, 538.95 and 257.66 is: 355.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.70 : 538.95 = 257.66 : x
  2. Step 2: Convert to fraction form
    390.70/538.95 = 257.66/x
  3. Step 3: Cross multiply
    390.70x = 538.95 × 257.66
  4. Step 4: Simplify right side
    390.70x = 138,863.00
  5. Step 5: Solve for x
    x = 138,863.00/390.70
  6. Step 6: Final answer
    x = 355.42

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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.