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Finding the Fourth Proportional to 920.15, 1,380.81 and 859.40

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Solution

The fourth proportional to 920.15, 1,380.81 and 859.40 is: 1,289.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.15 : 1,380.81 = 859.40 : x
  2. Step 2: Convert to fraction form
    920.15/1,380.81 = 859.40/x
  3. Step 3: Cross multiply
    920.15x = 1,380.81 × 859.40
  4. Step 4: Simplify right side
    920.15x = 1,186,668.11
  5. Step 5: Solve for x
    x = 1,186,668.11/920.15
  6. Step 6: Final answer
    x = 1,289.65

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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.