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Finding the Fourth Proportional to 917.82, 1,376.71 and 431.21

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Solution

The fourth proportional to 917.82, 1,376.71 and 431.21 is: 646.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    917.82 : 1,376.71 = 431.21 : x
  2. Step 2: Convert to fraction form
    917.82/1,376.71 = 431.21/x
  3. Step 3: Cross multiply
    917.82x = 1,376.71 × 431.21
  4. Step 4: Simplify right side
    917.82x = 593,651.12
  5. Step 5: Solve for x
    x = 593,651.12/917.82
  6. Step 6: Final answer
    x = 646.81

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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.