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Finding the Fourth Proportional to 1,390.84, 2,086.40 and 660.24

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Solution

The fourth proportional to 1,390.84, 2,086.40 and 660.24 is: 990.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.84 : 2,086.40 = 660.24 : x
  2. Step 2: Convert to fraction form
    1,390.84/2,086.40 = 660.24/x
  3. Step 3: Cross multiply
    1,390.84x = 2,086.40 × 660.24
  4. Step 4: Simplify right side
    1,390.84x = 1,377,524.74
  5. Step 5: Solve for x
    x = 1,377,524.74/1,390.84
  6. Step 6: Final answer
    x = 990.43

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.