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Finding the Fourth Proportional to 720.90, 1,080.40 and 355.78

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Solution

The fourth proportional to 720.90, 1,080.40 and 355.78 is: 533.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.90 : 1,080.40 = 355.78 : x
  2. Step 2: Convert to fraction form
    720.90/1,080.40 = 355.78/x
  3. Step 3: Cross multiply
    720.90x = 1,080.40 × 355.78
  4. Step 4: Simplify right side
    720.90x = 384,384.71
  5. Step 5: Solve for x
    x = 384,384.71/720.90
  6. Step 6: Final answer
    x = 533.20

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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.