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Finding the Fourth Proportional to 851.20, 1,275.90 and 485.20

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Solution

The fourth proportional to 851.20, 1,275.90 and 485.20 is: 727.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    851.20 : 1,275.90 = 485.20 : x
  2. Step 2: Convert to fraction form
    851.20/1,275.90 = 485.20/x
  3. Step 3: Cross multiply
    851.20x = 1,275.90 × 485.20
  4. Step 4: Simplify right side
    851.20x = 619,066.68
  5. Step 5: Solve for x
    x = 619,066.68/851.20
  6. Step 6: Final answer
    x = 727.29

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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.