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Finding the Fourth Proportional to 811.68, 1,219.14 and 721.50

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Solution

The fourth proportional to 811.68, 1,219.14 and 721.50 is: 1,083.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.68 : 1,219.14 = 721.50 : x
  2. Step 2: Convert to fraction form
    811.68/1,219.14 = 721.50/x
  3. Step 3: Cross multiply
    811.68x = 1,219.14 × 721.50
  4. Step 4: Simplify right side
    811.68x = 879,609.51
  5. Step 5: Solve for x
    x = 879,609.51/811.68
  6. Step 6: Final answer
    x = 1,083.69

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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.