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Finding the Fourth Proportional to 1,219.21, 1,682.20 and 721.64

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Solution

The fourth proportional to 1,219.21, 1,682.20 and 721.64 is: 995.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,219.21 : 1,682.20 = 721.64 : x
  2. Step 2: Convert to fraction form
    1,219.21/1,682.20 = 721.64/x
  3. Step 3: Cross multiply
    1,219.21x = 1,682.20 × 721.64
  4. Step 4: Simplify right side
    1,219.21x = 1,213,942.81
  5. Step 5: Solve for x
    x = 1,213,942.81/1,219.21
  6. Step 6: Final answer
    x = 995.68

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.