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Finding the Fourth Proportional to 1,218.92, 1,681.98 and 721.60

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Solution

The fourth proportional to 1,218.92, 1,681.98 and 721.60 is: 995.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.92 : 1,681.98 = 721.60 : x
  2. Step 2: Convert to fraction form
    1,218.92/1,681.98 = 721.60/x
  3. Step 3: Cross multiply
    1,218.92x = 1,681.98 × 721.60
  4. Step 4: Simplify right side
    1,218.92x = 1,213,716.77
  5. Step 5: Solve for x
    x = 1,213,716.77/1,218.92
  6. Step 6: Final answer
    x = 995.73

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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.