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Finding the Fourth Proportional to 919, 1,378.68 and 638.80

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Solution

The fourth proportional to 919, 1,378.68 and 638.80 is: 958.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    919 : 1,378.68 = 638.80 : x
  2. Step 2: Convert to fraction form
    919/1,378.68 = 638.80/x
  3. Step 3: Cross multiply
    919x = 1,378.68 × 638.80
  4. Step 4: Simplify right side
    919x = 880,700.78
  5. Step 5: Solve for x
    x = 880,700.78/919
  6. Step 6: Final answer
    x = 958.33

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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.