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Finding the Fourth Proportional to 780.11, 1,077.21 and 647.22

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Solution

The fourth proportional to 780.11, 1,077.21 and 647.22 is: 893.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.11 : 1,077.21 = 647.22 : x
  2. Step 2: Convert to fraction form
    780.11/1,077.21 = 647.22/x
  3. Step 3: Cross multiply
    780.11x = 1,077.21 × 647.22
  4. Step 4: Simplify right side
    780.11x = 697,191.86
  5. Step 5: Solve for x
    x = 697,191.86/780.11
  6. Step 6: Final answer
    x = 893.71

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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.