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Finding the Fourth Proportional to 859.66, 1,290.11 and 665.15

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Solution

The fourth proportional to 859.66, 1,290.11 and 665.15 is: 998.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.66 : 1,290.11 = 665.15 : x
  2. Step 2: Convert to fraction form
    859.66/1,290.11 = 665.15/x
  3. Step 3: Cross multiply
    859.66x = 1,290.11 × 665.15
  4. Step 4: Simplify right side
    859.66x = 858,106.89
  5. Step 5: Solve for x
    x = 858,106.89/859.66
  6. Step 6: Final answer
    x = 998.20

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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.