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Finding the Fourth Proportional to 987.90, 1,481.76 and 257.43

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Solution

The fourth proportional to 987.90, 1,481.76 and 257.43 is: 386.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.90 : 1,481.76 = 257.43 : x
  2. Step 2: Convert to fraction form
    987.90/1,481.76 = 257.43/x
  3. Step 3: Cross multiply
    987.90x = 1,481.76 × 257.43
  4. Step 4: Simplify right side
    987.90x = 381,449.48
  5. Step 5: Solve for x
    x = 381,449.48/987.90
  6. Step 6: Final answer
    x = 386.12

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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.