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Finding the Fourth Proportional to 759.42, 1,139.40 and 320.78

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Solution

The fourth proportional to 759.42, 1,139.40 and 320.78 is: 481.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    759.42 : 1,139.40 = 320.78 : x
  2. Step 2: Convert to fraction form
    759.42/1,139.40 = 320.78/x
  3. Step 3: Cross multiply
    759.42x = 1,139.40 × 320.78
  4. Step 4: Simplify right side
    759.42x = 365,491.04
  5. Step 5: Solve for x
    x = 365,491.04/759.42
  6. Step 6: Final answer
    x = 481.28

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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.