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Finding the Fourth Proportional to 780.07, 1,169.87 and 642.78

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Solution

The fourth proportional to 780.07, 1,169.87 and 642.78 is: 963.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.07 : 1,169.87 = 642.78 : x
  2. Step 2: Convert to fraction form
    780.07/1,169.87 = 642.78/x
  3. Step 3: Cross multiply
    780.07x = 1,169.87 × 642.78
  4. Step 4: Simplify right side
    780.07x = 751,963.19
  5. Step 5: Solve for x
    x = 751,963.19/780.07
  6. Step 6: Final answer
    x = 963.97

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.