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Finding the Fourth Proportional to 991.20, 1,368 and 618.58

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Solution

The fourth proportional to 991.20, 1,368 and 618.58 is: 853.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.20 : 1,368 = 618.58 : x
  2. Step 2: Convert to fraction form
    991.20/1,368 = 618.58/x
  3. Step 3: Cross multiply
    991.20x = 1,368 × 618.58
  4. Step 4: Simplify right side
    991.20x = 846,217.44
  5. Step 5: Solve for x
    x = 846,217.44/991.20
  6. Step 6: Final answer
    x = 853.73

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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.