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Finding the Fourth Proportional to 919.95, 1,269.28 and 639.87

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Solution

The fourth proportional to 919.95, 1,269.28 and 639.87 is: 882.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.95 : 1,269.28 = 639.87 : x
  2. Step 2: Convert to fraction form
    919.95/1,269.28 = 639.87/x
  3. Step 3: Cross multiply
    919.95x = 1,269.28 × 639.87
  4. Step 4: Simplify right side
    919.95x = 812,174.19
  5. Step 5: Solve for x
    x = 812,174.19/919.95
  6. Step 6: Final answer
    x = 882.85

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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.