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Finding the Fourth Proportional to 991.73, 1,487.30 and 685.55

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Solution

The fourth proportional to 991.73, 1,487.30 and 685.55 is: 1,028.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.73 : 1,487.30 = 685.55 : x
  2. Step 2: Convert to fraction form
    991.73/1,487.30 = 685.55/x
  3. Step 3: Cross multiply
    991.73x = 1,487.30 × 685.55
  4. Step 4: Simplify right side
    991.73x = 1,019,607.65
  5. Step 5: Solve for x
    x = 1,019,607.65/991.73
  6. Step 6: Final answer
    x = 1,028.12

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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.