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Finding the Fourth Proportional to 1,379.80, 2,069.90 and 455.20

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Solution

The fourth proportional to 1,379.80, 2,069.90 and 455.20 is: 682.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,379.80 : 2,069.90 = 455.20 : x
  2. Step 2: Convert to fraction form
    1,379.80/2,069.90 = 455.20/x
  3. Step 3: Cross multiply
    1,379.80x = 2,069.90 × 455.20
  4. Step 4: Simplify right side
    1,379.80x = 942,218.48
  5. Step 5: Solve for x
    x = 942,218.48/1,379.80
  6. Step 6: Final answer
    x = 682.87

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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.