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Finding the Fourth Proportional to 991.29, 1,367.79 and 636.66

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Solution

The fourth proportional to 991.29, 1,367.79 and 636.66 is: 878.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.29 : 1,367.79 = 636.66 : x
  2. Step 2: Convert to fraction form
    991.29/1,367.79 = 636.66/x
  3. Step 3: Cross multiply
    991.29x = 1,367.79 × 636.66
  4. Step 4: Simplify right side
    991.29x = 870,814.79
  5. Step 5: Solve for x
    x = 870,814.79/991.29
  6. Step 6: Final answer
    x = 878.47

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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.