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Finding the Fourth Proportional to 779.80, 1,077.66 and 639.70

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Solution

The fourth proportional to 779.80, 1,077.66 and 639.70 is: 884.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    779.80 : 1,077.66 = 639.70 : x
  2. Step 2: Convert to fraction form
    779.80/1,077.66 = 639.70/x
  3. Step 3: Cross multiply
    779.80x = 1,077.66 × 639.70
  4. Step 4: Simplify right side
    779.80x = 689,379.10
  5. Step 5: Solve for x
    x = 689,379.10/779.80
  6. Step 6: Final answer
    x = 884.05

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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.