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Finding the Fourth Proportional to 990.68, 1,366.86 and 641.48

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Solution

The fourth proportional to 990.68, 1,366.86 and 641.48 is: 885.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.68 : 1,366.86 = 641.48 : x
  2. Step 2: Convert to fraction form
    990.68/1,366.86 = 641.48/x
  3. Step 3: Cross multiply
    990.68x = 1,366.86 × 641.48
  4. Step 4: Simplify right side
    990.68x = 876,813.35
  5. Step 5: Solve for x
    x = 876,813.35/990.68
  6. Step 6: Final answer
    x = 885.06

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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.