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Finding the Fourth Proportional to 390.32, 538.78 and 257.91

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Solution

The fourth proportional to 390.32, 538.78 and 257.91 is: 356.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.32 : 538.78 = 257.91 : x
  2. Step 2: Convert to fraction form
    390.32/538.78 = 257.91/x
  3. Step 3: Cross multiply
    390.32x = 538.78 × 257.91
  4. Step 4: Simplify right side
    390.32x = 138,952.77
  5. Step 5: Solve for x
    x = 138,952.77/390.32
  6. Step 6: Final answer
    x = 356.00

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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.