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Finding the Fourth Proportional to 991.75, 1,487.61 and 261.31

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Solution

The fourth proportional to 991.75, 1,487.61 and 261.31 is: 391.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.75 : 1,487.61 = 261.31 : x
  2. Step 2: Convert to fraction form
    991.75/1,487.61 = 261.31/x
  3. Step 3: Cross multiply
    991.75x = 1,487.61 × 261.31
  4. Step 4: Simplify right side
    991.75x = 388,727.37
  5. Step 5: Solve for x
    x = 388,727.37/991.75
  6. Step 6: Final answer
    x = 391.96

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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.