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Finding the Fourth Proportional to 991.26, 1,367.67 and 642.30

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Solution

The fourth proportional to 991.26, 1,367.67 and 642.30 is: 886.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.26 : 1,367.67 = 642.30 : x
  2. Step 2: Convert to fraction form
    991.26/1,367.67 = 642.30/x
  3. Step 3: Cross multiply
    991.26x = 1,367.67 × 642.30
  4. Step 4: Simplify right side
    991.26x = 878,454.44
  5. Step 5: Solve for x
    x = 878,454.44/991.26
  6. Step 6: Final answer
    x = 886.20

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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.