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Finding the Fourth Proportional to 778.50, 1,075.86 and 638.39

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Solution

The fourth proportional to 778.50, 1,075.86 and 638.39 is: 882.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    778.50 : 1,075.86 = 638.39 : x
  2. Step 2: Convert to fraction form
    778.50/1,075.86 = 638.39/x
  3. Step 3: Cross multiply
    778.50x = 1,075.86 × 638.39
  4. Step 4: Simplify right side
    778.50x = 686,820.96
  5. Step 5: Solve for x
    x = 686,820.96/778.50
  6. Step 6: Final answer
    x = 882.24

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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.