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Finding the Fourth Proportional to 1,239.97, 1,712.31 and 990.49

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Solution

The fourth proportional to 1,239.97, 1,712.31 and 990.49 is: 1,367.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.97 : 1,712.31 = 990.49 : x
  2. Step 2: Convert to fraction form
    1,239.97/1,712.31 = 990.49/x
  3. Step 3: Cross multiply
    1,239.97x = 1,712.31 × 990.49
  4. Step 4: Simplify right side
    1,239.97x = 1,696,025.93
  5. Step 5: Solve for x
    x = 1,696,025.93/1,239.97
  6. Step 6: Final answer
    x = 1,367.80

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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.