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Finding the Fourth Proportional to 851.58, 1,278.18 and 389.88

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Solution

The fourth proportional to 851.58, 1,278.18 and 389.88 is: 585.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    851.58 : 1,278.18 = 389.88 : x
  2. Step 2: Convert to fraction form
    851.58/1,278.18 = 389.88/x
  3. Step 3: Cross multiply
    851.58x = 1,278.18 × 389.88
  4. Step 4: Simplify right side
    851.58x = 498,336.82
  5. Step 5: Solve for x
    x = 498,336.82/851.58
  6. Step 6: Final answer
    x = 585.19

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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.