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Finding the Fourth Proportional to 990.20, 1,365.44 and 691.80

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Solution

The fourth proportional to 990.20, 1,365.44 and 691.80 is: 953.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.20 : 1,365.44 = 691.80 : x
  2. Step 2: Convert to fraction form
    990.20/1,365.44 = 691.80/x
  3. Step 3: Cross multiply
    990.20x = 1,365.44 × 691.80
  4. Step 4: Simplify right side
    990.20x = 944,611.39
  5. Step 5: Solve for x
    x = 944,611.39/990.20
  6. Step 6: Final answer
    x = 953.96

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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.