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Finding the Fourth Proportional to 1,327.40, 1,991.10 and 839.78

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Solution

The fourth proportional to 1,327.40, 1,991.10 and 839.78 is: 1,259.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,327.40 : 1,991.10 = 839.78 : x
  2. Step 2: Convert to fraction form
    1,327.40/1,991.10 = 839.78/x
  3. Step 3: Cross multiply
    1,327.40x = 1,991.10 × 839.78
  4. Step 4: Simplify right side
    1,327.40x = 1,672,085.96
  5. Step 5: Solve for x
    x = 1,672,085.96/1,327.40
  6. Step 6: Final answer
    x = 1,259.67

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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.