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Finding the Fourth Proportional to 917.79, 1,375.25 and 639.87

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Solution

The fourth proportional to 917.79, 1,375.25 and 639.87 is: 958.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    917.79 : 1,375.25 = 639.87 : x
  2. Step 2: Convert to fraction form
    917.79/1,375.25 = 639.87/x
  3. Step 3: Cross multiply
    917.79x = 1,375.25 × 639.87
  4. Step 4: Simplify right side
    917.79x = 879,978.02
  5. Step 5: Solve for x
    x = 879,978.02/917.79
  6. Step 6: Final answer
    x = 958.80

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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.