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Finding the Fourth Proportional to 807.20, 1,210.80 and 685.70

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Solution

The fourth proportional to 807.20, 1,210.80 and 685.70 is: 1,028.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    807.20 : 1,210.80 = 685.70 : x
  2. Step 2: Convert to fraction form
    807.20/1,210.80 = 685.70/x
  3. Step 3: Cross multiply
    807.20x = 1,210.80 × 685.70
  4. Step 4: Simplify right side
    807.20x = 830,245.56
  5. Step 5: Solve for x
    x = 830,245.56/807.20
  6. Step 6: Final answer
    x = 1,028.55

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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.