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Finding the Fourth Proportional to 939.20, 1,406 and 696.80

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Solution

The fourth proportional to 939.20, 1,406 and 696.80 is: 1,043.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.20 : 1,406 = 696.80 : x
  2. Step 2: Convert to fraction form
    939.20/1,406 = 696.80/x
  3. Step 3: Cross multiply
    939.20x = 1,406 × 696.80
  4. Step 4: Simplify right side
    939.20x = 979,700.80
  5. Step 5: Solve for x
    x = 979,700.80/939.20
  6. Step 6: Final answer
    x = 1,043.12

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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.