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Finding the Fourth Proportional to 1,391.08, 2,085.60 and 659.80

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Solution

The fourth proportional to 1,391.08, 2,085.60 and 659.80 is: 989.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.08 : 2,085.60 = 659.80 : x
  2. Step 2: Convert to fraction form
    1,391.08/2,085.60 = 659.80/x
  3. Step 3: Cross multiply
    1,391.08x = 2,085.60 × 659.80
  4. Step 4: Simplify right side
    1,391.08x = 1,376,078.88
  5. Step 5: Solve for x
    x = 1,376,078.88/1,391.08
  6. Step 6: Final answer
    x = 989.22

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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.