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Finding the Fourth Proportional to 990.71, 1,366.78 and 636.57

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Solution

The fourth proportional to 990.71, 1,366.78 and 636.57 is: 878.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.71 : 1,366.78 = 636.57 : x
  2. Step 2: Convert to fraction form
    990.71/1,366.78 = 636.57/x
  3. Step 3: Cross multiply
    990.71x = 1,366.78 × 636.57
  4. Step 4: Simplify right side
    990.71x = 870,054.56
  5. Step 5: Solve for x
    x = 870,054.56/990.71
  6. Step 6: Final answer
    x = 878.22

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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.