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Finding the Fourth Proportional to 851.40, 1,276.80 and 389.40

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Solution

The fourth proportional to 851.40, 1,276.80 and 389.40 is: 583.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    851.40 : 1,276.80 = 389.40 : x
  2. Step 2: Convert to fraction form
    851.40/1,276.80 = 389.40/x
  3. Step 3: Cross multiply
    851.40x = 1,276.80 × 389.40
  4. Step 4: Simplify right side
    851.40x = 497,185.92
  5. Step 5: Solve for x
    x = 497,185.92/851.40
  6. Step 6: Final answer
    x = 583.96

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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.