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Finding the Fourth Proportional to 1,380.50, 2,070.01 and 720.78

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Solution

The fourth proportional to 1,380.50, 2,070.01 and 720.78 is: 1,080.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,380.50 : 2,070.01 = 720.78 : x
  2. Step 2: Convert to fraction form
    1,380.50/2,070.01 = 720.78/x
  3. Step 3: Cross multiply
    1,380.50x = 2,070.01 × 720.78
  4. Step 4: Simplify right side
    1,380.50x = 1,492,027.18
  5. Step 5: Solve for x
    x = 1,492,027.18/1,380.50
  6. Step 6: Final answer
    x = 1,080.79

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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.