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Finding the Fourth Proportional to 857.46, 1,287.63 and 813.62

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Solution

The fourth proportional to 857.46, 1,287.63 and 813.62 is: 1,221.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.46 : 1,287.63 = 813.62 : x
  2. Step 2: Convert to fraction form
    857.46/1,287.63 = 813.62/x
  3. Step 3: Cross multiply
    857.46x = 1,287.63 × 813.62
  4. Step 4: Simplify right side
    857.46x = 1,047,641.52
  5. Step 5: Solve for x
    x = 1,047,641.52/857.46
  6. Step 6: Final answer
    x = 1,221.80

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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.