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Finding the Fourth Proportional to 1,079.60, 1,620.70 and 689.60

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Solution

The fourth proportional to 1,079.60, 1,620.70 and 689.60 is: 1,035.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,079.60 : 1,620.70 = 689.60 : x
  2. Step 2: Convert to fraction form
    1,079.60/1,620.70 = 689.60/x
  3. Step 3: Cross multiply
    1,079.60x = 1,620.70 × 689.60
  4. Step 4: Simplify right side
    1,079.60x = 1,117,634.72
  5. Step 5: Solve for x
    x = 1,117,634.72/1,079.60
  6. Step 6: Final answer
    x = 1,035.23

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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.