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Finding the Fourth Proportional to 1,390.26, 2,085.84 and 660

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Solution

The fourth proportional to 1,390.26, 2,085.84 and 660 is: 990.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.26 : 2,085.84 = 660 : x
  2. Step 2: Convert to fraction form
    1,390.26/2,085.84 = 660/x
  3. Step 3: Cross multiply
    1,390.26x = 2,085.84 × 660
  4. Step 4: Simplify right side
    1,390.26x = 1,376,654.40
  5. Step 5: Solve for x
    x = 1,376,654.40/1,390.26
  6. Step 6: Final answer
    x = 990.21

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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.