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Finding the Fourth Proportional to 1,321.45, 1,980.80 and 771.96

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Solution

The fourth proportional to 1,321.45, 1,980.80 and 771.96 is: 1,157.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.45 : 1,980.80 = 771.96 : x
  2. Step 2: Convert to fraction form
    1,321.45/1,980.80 = 771.96/x
  3. Step 3: Cross multiply
    1,321.45x = 1,980.80 × 771.96
  4. Step 4: Simplify right side
    1,321.45x = 1,529,100.30
  5. Step 5: Solve for x
    x = 1,529,100.30/1,321.45
  6. Step 6: Final answer
    x = 1,157.14

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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.