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Finding the Fourth Proportional to 999.45, 1,378.77 and 667.98

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Solution

The fourth proportional to 999.45, 1,378.77 and 667.98 is: 921.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.45 : 1,378.77 = 667.98 : x
  2. Step 2: Convert to fraction form
    999.45/1,378.77 = 667.98/x
  3. Step 3: Cross multiply
    999.45x = 1,378.77 × 667.98
  4. Step 4: Simplify right side
    999.45x = 920,990.78
  5. Step 5: Solve for x
    x = 920,990.78/999.45
  6. Step 6: Final answer
    x = 921.50

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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.