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Finding the Fourth Proportional to 779.80, 1,169.70 and 720.40

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Solution

The fourth proportional to 779.80, 1,169.70 and 720.40 is: 1,080.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    779.80 : 1,169.70 = 720.40 : x
  2. Step 2: Convert to fraction form
    779.80/1,169.70 = 720.40/x
  3. Step 3: Cross multiply
    779.80x = 1,169.70 × 720.40
  4. Step 4: Simplify right side
    779.80x = 842,651.88
  5. Step 5: Solve for x
    x = 842,651.88/779.80
  6. Step 6: Final answer
    x = 1,080.60

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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.