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Finding the Fourth Proportional to 1,079.40, 1,620.60 and 691.80

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Solution

The fourth proportional to 1,079.40, 1,620.60 and 691.80 is: 1,038.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,079.40 : 1,620.60 = 691.80 : x
  2. Step 2: Convert to fraction form
    1,079.40/1,620.60 = 691.80/x
  3. Step 3: Cross multiply
    1,079.40x = 1,620.60 × 691.80
  4. Step 4: Simplify right side
    1,079.40x = 1,121,131.08
  5. Step 5: Solve for x
    x = 1,121,131.08/1,079.40
  6. Step 6: Final answer
    x = 1,038.66

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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.