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Finding the Fourth Proportional to 999, 1,378.89 and 688.50

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Solution

The fourth proportional to 999, 1,378.89 and 688.50 is: 950.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    999 : 1,378.89 = 688.50 : x
  2. Step 2: Convert to fraction form
    999/1,378.89 = 688.50/x
  3. Step 3: Cross multiply
    999x = 1,378.89 × 688.50
  4. Step 4: Simplify right side
    999x = 949,365.77
  5. Step 5: Solve for x
    x = 949,365.77/999
  6. Step 6: Final answer
    x = 950.32

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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.