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Finding the Fourth Proportional to 257.12, 387.45 and 212.47

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Solution

The fourth proportional to 257.12, 387.45 and 212.47 is: 320.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.12 : 387.45 = 212.47 : x
  2. Step 2: Convert to fraction form
    257.12/387.45 = 212.47/x
  3. Step 3: Cross multiply
    257.12x = 387.45 × 212.47
  4. Step 4: Simplify right side
    257.12x = 82,322.71
  5. Step 5: Solve for x
    x = 82,322.71/257.12
  6. Step 6: Final answer
    x = 320.17

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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.