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Finding the Fourth Proportional to 928.45, 1,389.43 and 640.09

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Solution

The fourth proportional to 928.45, 1,389.43 and 640.09 is: 957.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.45 : 1,389.43 = 640.09 : x
  2. Step 2: Convert to fraction form
    928.45/1,389.43 = 640.09/x
  3. Step 3: Cross multiply
    928.45x = 1,389.43 × 640.09
  4. Step 4: Simplify right side
    928.45x = 889,360.25
  5. Step 5: Solve for x
    x = 889,360.25/928.45
  6. Step 6: Final answer
    x = 957.90

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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.