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Finding the Fourth Proportional to 999.81, 1,379.94 and 685.17

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Solution

The fourth proportional to 999.81, 1,379.94 and 685.17 is: 945.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.81 : 1,379.94 = 685.17 : x
  2. Step 2: Convert to fraction form
    999.81/1,379.94 = 685.17/x
  3. Step 3: Cross multiply
    999.81x = 1,379.94 × 685.17
  4. Step 4: Simplify right side
    999.81x = 945,493.49
  5. Step 5: Solve for x
    x = 945,493.49/999.81
  6. Step 6: Final answer
    x = 945.67

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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.