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Finding the Fourth Proportional to 781.89, 1,080.54 and 641.79

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Solution

The fourth proportional to 781.89, 1,080.54 and 641.79 is: 886.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.89 : 1,080.54 = 641.79 : x
  2. Step 2: Convert to fraction form
    781.89/1,080.54 = 641.79/x
  3. Step 3: Cross multiply
    781.89x = 1,080.54 × 641.79
  4. Step 4: Simplify right side
    781.89x = 693,479.77
  5. Step 5: Solve for x
    x = 693,479.77/781.89
  6. Step 6: Final answer
    x = 886.93

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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.