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Finding the Fourth Proportional to 991.90, 1,368.57 and 618.85

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Solution

The fourth proportional to 991.90, 1,368.57 and 618.85 is: 853.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.90 : 1,368.57 = 618.85 : x
  2. Step 2: Convert to fraction form
    991.90/1,368.57 = 618.85/x
  3. Step 3: Cross multiply
    991.90x = 1,368.57 × 618.85
  4. Step 4: Simplify right side
    991.90x = 846,939.54
  5. Step 5: Solve for x
    x = 846,939.54/991.90
  6. Step 6: Final answer
    x = 853.86

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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.