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Finding the Fourth Proportional to 991.89, 1,369.25 and 618.80

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Solution

The fourth proportional to 991.89, 1,369.25 and 618.80 is: 854.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.89 : 1,369.25 = 618.80 : x
  2. Step 2: Convert to fraction form
    991.89/1,369.25 = 618.80/x
  3. Step 3: Cross multiply
    991.89x = 1,369.25 × 618.80
  4. Step 4: Simplify right side
    991.89x = 847,281.96
  5. Step 5: Solve for x
    x = 847,281.96/991.89
  6. Step 6: Final answer
    x = 854.21

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.