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Finding the Fourth Proportional to 991.38, 1,486.80 and 699.78

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Solution

The fourth proportional to 991.38, 1,486.80 and 699.78 is: 1,049.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.38 : 1,486.80 = 699.78 : x
  2. Step 2: Convert to fraction form
    991.38/1,486.80 = 699.78/x
  3. Step 3: Cross multiply
    991.38x = 1,486.80 × 699.78
  4. Step 4: Simplify right side
    991.38x = 1,040,432.90
  5. Step 5: Solve for x
    x = 1,040,432.90/991.38
  6. Step 6: Final answer
    x = 1,049.48

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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.