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Finding the Fourth Proportional to 991.20, 1,367.04 and 642.24

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Solution

The fourth proportional to 991.20, 1,367.04 and 642.24 is: 885.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.20 : 1,367.04 = 642.24 : x
  2. Step 2: Convert to fraction form
    991.20/1,367.04 = 642.24/x
  3. Step 3: Cross multiply
    991.20x = 1,367.04 × 642.24
  4. Step 4: Simplify right side
    991.20x = 877,967.77
  5. Step 5: Solve for x
    x = 877,967.77/991.20
  6. Step 6: Final answer
    x = 885.76

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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.