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Finding the Fourth Proportional to 859.30, 1,284.90 and 640.60

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Solution

The fourth proportional to 859.30, 1,284.90 and 640.60 is: 957.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.30 : 1,284.90 = 640.60 : x
  2. Step 2: Convert to fraction form
    859.30/1,284.90 = 640.60/x
  3. Step 3: Cross multiply
    859.30x = 1,284.90 × 640.60
  4. Step 4: Simplify right side
    859.30x = 823,106.94
  5. Step 5: Solve for x
    x = 823,106.94/859.30
  6. Step 6: Final answer
    x = 957.88

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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.