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Finding the Fourth Proportional to 720.80, 1,081.20 and 715.40

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Solution

The fourth proportional to 720.80, 1,081.20 and 715.40 is: 1,073.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.80 : 1,081.20 = 715.40 : x
  2. Step 2: Convert to fraction form
    720.80/1,081.20 = 715.40/x
  3. Step 3: Cross multiply
    720.80x = 1,081.20 × 715.40
  4. Step 4: Simplify right side
    720.80x = 773,490.48
  5. Step 5: Solve for x
    x = 773,490.48/720.80
  6. Step 6: Final answer
    x = 1,073.10

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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.