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Finding the Fourth Proportional to 720.40, 1,078.20 and 662.80

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Solution

The fourth proportional to 720.40, 1,078.20 and 662.80 is: 991.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.40 : 1,078.20 = 662.80 : x
  2. Step 2: Convert to fraction form
    720.40/1,078.20 = 662.80/x
  3. Step 3: Cross multiply
    720.40x = 1,078.20 × 662.80
  4. Step 4: Simplify right side
    720.40x = 714,630.96
  5. Step 5: Solve for x
    x = 714,630.96/720.40
  6. Step 6: Final answer
    x = 991.99

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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.