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Finding the Fourth Proportional to 813.68, 1,218.75 and 721.41

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Solution

The fourth proportional to 813.68, 1,218.75 and 721.41 is: 1,080.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.68 : 1,218.75 = 721.41 : x
  2. Step 2: Convert to fraction form
    813.68/1,218.75 = 721.41/x
  3. Step 3: Cross multiply
    813.68x = 1,218.75 × 721.41
  4. Step 4: Simplify right side
    813.68x = 879,211.16
  5. Step 5: Solve for x
    x = 879,211.16/813.68
  6. Step 6: Final answer
    x = 1,080.54

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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.