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Finding the Fourth Proportional to 860.65, 1,188.42 and 640.59

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Solution

The fourth proportional to 860.65, 1,188.42 and 640.59 is: 884.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.65 : 1,188.42 = 640.59 : x
  2. Step 2: Convert to fraction form
    860.65/1,188.42 = 640.59/x
  3. Step 3: Cross multiply
    860.65x = 1,188.42 × 640.59
  4. Step 4: Simplify right side
    860.65x = 761,289.97
  5. Step 5: Solve for x
    x = 761,289.97/860.65
  6. Step 6: Final answer
    x = 884.55

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.