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Finding the Fourth Proportional to 1,320.88, 1,981.72 and 771.90

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Solution

The fourth proportional to 1,320.88, 1,981.72 and 771.90 is: 1,158.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.88 : 1,981.72 = 771.90 : x
  2. Step 2: Convert to fraction form
    1,320.88/1,981.72 = 771.90/x
  3. Step 3: Cross multiply
    1,320.88x = 1,981.72 × 771.90
  4. Step 4: Simplify right side
    1,320.88x = 1,529,690.63
  5. Step 5: Solve for x
    x = 1,529,690.63/1,320.88
  6. Step 6: Final answer
    x = 1,158.09

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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.