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Finding the Fourth Proportional to 783.89, 1,080.31 and 643.19

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Solution

The fourth proportional to 783.89, 1,080.31 and 643.19 is: 886.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    783.89 : 1,080.31 = 643.19 : x
  2. Step 2: Convert to fraction form
    783.89/1,080.31 = 643.19/x
  3. Step 3: Cross multiply
    783.89x = 1,080.31 × 643.19
  4. Step 4: Simplify right side
    783.89x = 694,844.59
  5. Step 5: Solve for x
    x = 694,844.59/783.89
  6. Step 6: Final answer
    x = 886.41

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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.