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Finding the Fourth Proportional to 991.46, 1,367.64 and 642.14

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Solution

The fourth proportional to 991.46, 1,367.64 and 642.14 is: 885.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.46 : 1,367.64 = 642.14 : x
  2. Step 2: Convert to fraction form
    991.46/1,367.64 = 642.14/x
  3. Step 3: Cross multiply
    991.46x = 1,367.64 × 642.14
  4. Step 4: Simplify right side
    991.46x = 878,216.35
  5. Step 5: Solve for x
    x = 878,216.35/991.46
  6. Step 6: Final answer
    x = 885.78

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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.