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Finding the Fourth Proportional to 991.43, 1,487.22 and 261

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Solution

The fourth proportional to 991.43, 1,487.22 and 261 is: 391.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.43 : 1,487.22 = 261 : x
  2. Step 2: Convert to fraction form
    991.43/1,487.22 = 261/x
  3. Step 3: Cross multiply
    991.43x = 1,487.22 × 261
  4. Step 4: Simplify right side
    991.43x = 388,163.44
  5. Step 5: Solve for x
    x = 388,163.44/991.43
  6. Step 6: Final answer
    x = 391.52

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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.