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Finding the Fourth Proportional to 780.01, 1,169.78 and 642.71

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Solution

The fourth proportional to 780.01, 1,169.78 and 642.71 is: 963.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.01 : 1,169.78 = 642.71 : x
  2. Step 2: Convert to fraction form
    780.01/1,169.78 = 642.71/x
  3. Step 3: Cross multiply
    780.01x = 1,169.78 × 642.71
  4. Step 4: Simplify right side
    780.01x = 751,829.30
  5. Step 5: Solve for x
    x = 751,829.30/780.01
  6. Step 6: Final answer
    x = 963.88

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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.