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Finding the Fourth Proportional to 920.40, 1,380.75 and 458.20

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Solution

The fourth proportional to 920.40, 1,380.75 and 458.20 is: 687.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.40 : 1,380.75 = 458.20 : x
  2. Step 2: Convert to fraction form
    920.40/1,380.75 = 458.20/x
  3. Step 3: Cross multiply
    920.40x = 1,380.75 × 458.20
  4. Step 4: Simplify right side
    920.40x = 632,659.65
  5. Step 5: Solve for x
    x = 632,659.65/920.40
  6. Step 6: Final answer
    x = 687.37

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1.5x scale

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.