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Finding the Fourth Proportional to 991.98, 1,489.59 and 855.90

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Solution

The fourth proportional to 991.98, 1,489.59 and 855.90 is: 1,285.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.98 : 1,489.59 = 855.90 : x
  2. Step 2: Convert to fraction form
    991.98/1,489.59 = 855.90/x
  3. Step 3: Cross multiply
    991.98x = 1,489.59 × 855.90
  4. Step 4: Simplify right side
    991.98x = 1,274,940.08
  5. Step 5: Solve for x
    x = 1,274,940.08/991.98
  6. Step 6: Final answer
    x = 1,285.25

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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.