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Finding the Fourth Proportional to 257.58, 386.40 and 84.20

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Solution

The fourth proportional to 257.58, 386.40 and 84.20 is: 126.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.58 : 386.40 = 84.20 : x
  2. Step 2: Convert to fraction form
    257.58/386.40 = 84.20/x
  3. Step 3: Cross multiply
    257.58x = 386.40 × 84.20
  4. Step 4: Simplify right side
    257.58x = 32,534.88
  5. Step 5: Solve for x
    x = 32,534.88/257.58
  6. Step 6: Final answer
    x = 126.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.