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Finding the Fourth Proportional to 3,990.80, 5,391.90 and 3,990.80

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Solution

The fourth proportional to 3,990.80, 5,391.90 and 3,990.80 is: 5,391.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,990.80 : 5,391.90 = 3,990.80 : x
  2. Step 2: Convert to fraction form
    3,990.80/5,391.90 = 3,990.80/x
  3. Step 3: Cross multiply
    3,990.80x = 5,391.90 × 3,990.80
  4. Step 4: Simplify right side
    3,990.80x = 21,517,994.52
  5. Step 5: Solve for x
    x = 21,517,994.52/3,990.80
  6. Step 6: Final answer
    x = 5,391.90

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.35) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.