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Finding the Fourth Proportional to 783.81, 1,081.34 and 721.64

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Solution

The fourth proportional to 783.81, 1,081.34 and 721.64 is: 995.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    783.81 : 1,081.34 = 721.64 : x
  2. Step 2: Convert to fraction form
    783.81/1,081.34 = 721.64/x
  3. Step 3: Cross multiply
    783.81x = 1,081.34 × 721.64
  4. Step 4: Simplify right side
    783.81x = 780,338.20
  5. Step 5: Solve for x
    x = 780,338.20/783.81
  6. Step 6: Final answer
    x = 995.57

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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.