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Finding the Fourth Proportional to 859.80, 1,287.90 and 697.80

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Solution

The fourth proportional to 859.80, 1,287.90 and 697.80 is: 1,045.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.80 : 1,287.90 = 697.80 : x
  2. Step 2: Convert to fraction form
    859.80/1,287.90 = 697.80/x
  3. Step 3: Cross multiply
    859.80x = 1,287.90 × 697.80
  4. Step 4: Simplify right side
    859.80x = 898,696.62
  5. Step 5: Solve for x
    x = 898,696.62/859.80
  6. Step 6: Final answer
    x = 1,045.24

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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.