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Finding the Fourth Proportional to 390.53, 538.70 and 257.69

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Solution

The fourth proportional to 390.53, 538.70 and 257.69 is: 355.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.53 : 538.70 = 257.69 : x
  2. Step 2: Convert to fraction form
    390.53/538.70 = 257.69/x
  3. Step 3: Cross multiply
    390.53x = 538.70 × 257.69
  4. Step 4: Simplify right side
    390.53x = 138,813.62
  5. Step 5: Solve for x
    x = 138,813.62/390.53
  6. Step 6: Final answer
    x = 355.45

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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.