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Finding the Fourth Proportional to 931.72, 1,286.32 and 644.80

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Solution

The fourth proportional to 931.72, 1,286.32 and 644.80 is: 890.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.72 : 1,286.32 = 644.80 : x
  2. Step 2: Convert to fraction form
    931.72/1,286.32 = 644.80/x
  3. Step 3: Cross multiply
    931.72x = 1,286.32 × 644.80
  4. Step 4: Simplify right side
    931.72x = 829,419.14
  5. Step 5: Solve for x
    x = 829,419.14/931.72
  6. Step 6: Final answer
    x = 890.20

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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.